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author | Norbert Preining <norbert@preining.info> | 2021-05-27 03:01:40 +0000 |
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committer | Norbert Preining <norbert@preining.info> | 2021-05-27 03:01:40 +0000 |
commit | 5f1cfa686748068fedb95d8dafda3dc7f999c948 (patch) | |
tree | 874fa8430be12fe4633924f3b707428170316a46 /info/digests/tex-implementors/message.45 | |
parent | 8982c52e00ffb3fb5a913fc60913ebd9070f091a (diff) |
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diff --git a/info/digests/tex-implementors/message.45 b/info/digests/tex-implementors/message.45 new file mode 100644 index 0000000000..42c30a48a7 --- /dev/null +++ b/info/digests/tex-implementors/message.45 @@ -0,0 +1,1596 @@ +TeX 3.14159 and other updates -- file 2 of 2 + +######################################################################## + +>>> plain.tex + + +++ \oalign and \d{} + +[ the following two reports, from j"org knappen and petr sojka, + cover the same territory, but with different proposals for fixing +[ dek -- ^^^^^^^^^^^^^^ _different_ bugs in the same territory +] + the problem. i've included both since both looked reasonable to me. +] +------- +Newsgroups: comp.text.tex +Date: 17 May 1992 20:28:21 +0000 (GMT) +[ dek -- 1992 again -- I changed \d in 1993 but never had heard of this +] +Organization: Computer Science Dept, University of Tennesee, Knoxville +From: eijkhout@cupid.cs.utk.edu (Victor Eijkhout) +Subject: Re: \d{} + +In article <01GK1PHMODB48WWBZV@VzdmzA.ZDV.Uni-Mainz.DE>, + KNAPPEN@VKPMZD.KPH.Uni-Mainz.de (J%org Knappen) writes: +|> The following line +|> +|> Das ist ein Test von (\d{}) \verb:(\d{}): +|> +|> runs through TeX without any error messages, but produces an underdot which +|> is more than 300pt left off the paper. + +About 1000pt left of the opening bracket to be a bit more precise. + +|> \d{ } also fails, \d{\ } works and +|> produces a dot under ``nothing''. +|> +|> The test above turns out to be a driver's test, too. Two of four +|> dvi-drivers (on our VAX/VMS-system) did not complain nor show the mistake +|> in output. + +What mistake? How can a device driver know that your printer doesn' +have paper 1 meter wide? (With the margin only 20 cm from the right +paper edge :-) + +|> I consider the facts above as a misfeature (not to say bug). + +I consider the posting above as uninformed. + +But seriously, one might wonder what happens here. + +Watch this: + +This is TeX, C Version 3.0 +(/usr/local/lib/TeX/inputs/nul.tex +LaTeX Version 2.09 <7 Dec 1989> +) +*\show\d +> \d=macro: +->\protect \pd . +<*> \show\d + +? i\show\pd +> \pd=macro: +#1->\oalign {#1\crcr \hidewidth .\hidewidth }. +<insert> \show\pd + +(Yes, that's true, I run TeX interactively. I must be just about +the only one on earth to do this.) + +This tells you that \d is essentially a macro with one argument. +You give it the empty argument, so it expands to + \oalign { \crcr \hidewidth .\hidewidth } + +Now, \oalign is essentially \halign, and we know (otherwise look it up) +that \crcr only gives a new line if there was a line to terminate. +Which there isn't in this case, so we get + \halign { \hidewidth .\hidewidth } +[ dek -- ^ \preamble\cr +] + +and since \hidewidth is \hskip -1000pt plus 1fil, you have managed to +move the . 1000pt left of where you intended it to be. + +All of this does make me wonder a bit, though. Why did Knuth use \hidewidth? +Well obviously so that you could put objects under 'nothing'. +[ dek -- under very _narrow_ things +] +But why then \crcr and not just \cr? Well, probably he foresaw +that people might want to put stuff under more than one line, so both +\d{a\cr b} and \d{a\cr b\cr} had to give the same result. + +Hey, waddaya know! Everything is logical after all! + +|> Yours, J"org Knappen. + +Victor. +------- +X-ListName: TeX-Related Network Discussion List <INFO-TeX@SHSU.edu> +Date: 21 May 1992 12:46 +0000 (GMT) +From: J%org Knappen <KNAPPEN@VKPMZD.KPH.Uni-Mainz.de> +Subject: Again \d{}, with a bug fix + + Dear samretanoj, + + After reading Victor's posting carefully, the following bug fix comes to my + mind: +\def\d#1{\oalign{\null#1\crcr\hidewidth.\hidewidth}} +[ dek -- ^^^^^ \relax is better +] + (Barbara, are you listening? Please forward it to DEK) + + It passes the following tests: +Teste \d{}, \d{ }, \d{\ }! + +Mehr Tests: \d{a\cr b} und \d{a\cr b\cr}! +\bye + An analogous fix should be done to \b, both in plain.tex and lplain.tex. + + On drivers: + here is how a good driver (Brian {Hamilton Kelly}'s DVItoLN03) behaves: +This is DVItoLN03, Vax/VMS Version 4.0-3 +[Some more message stuff deleted (JK)] +Warning: Characters '' set off paper +( x = -3768..-3768, y = 342 ) - ignored +Warning: Characters '.' set off paper +( x = -3768..-3756, y = 342 ) - ignored +[153] Warning: Page wider than TeX reported by 510.2450pt + + Yours, J"org Knappen. + + P.S. Originally, I asked my question on the info-tex mailing list. The most + valuable contributions were only sent to the news group comp.text.tex. + Fortunately since one month I have also access to news...I must have missed + much before, even follow-ups to my own postings! +------- +Date: 12 Jan 1995 22:55:33 +0100 (MET) +From: Petr Sojka <sojka@daeron.ics.muni.cz> +Organization: Masaryk University, Brno, The Czech Republic +Subject: Bug in plain.tex -- please pass to DEK + +Barbara, + +here is what I consider as a bug of plain.tex: +You read there: + +% This is the plain TeX format that's described in The TeXbook. +% N.B.: A version number is defined at the very end of this file; +% please change that number whenever the file is modified! +% And don't modify the file under any circumstances. + +... + +\def\oalign#1{\leavevmode\vtop{\baselineskip\z@skip \lineskip.25ex% + \ialign{##\crcr#1\crcr}}} % put characters over each other +\def\ooalign{\lineskiplimit-\maxdimen \oalign} +\def\sh@ft#1{\dimen\z@.00#1ex\multiply\dimen\z@\fontdimen1\font + \kern-.0156\dimen\z@} % compensate for slant in lowered accents +\def\d#1{\oalign{#1\crcr\hidewidth\sh@ft{08}.\hidewidth}} +\def\b#1{\oalign{#1\crcr\hidewidth\sh@ft{29}% + \vbox to.2ex{\hbox{\char22}\vss}\hidewidth}} +\def\c#1{\setbox\z@\hbox{#1}\ifdim\ht\z@=1ex\accent24 #1% + \else{\ooalign{\unhbox\z@\crcr\hidewidth\char24\hidewidth}}\fi} +\def\copyright{{\ooalign{\hfil\raise.07ex\hbox{c}\hfil\crcr\mathhexbox20D}}} + +Simply saying, Don forgot setting of \lineskiplimit to zero +in \oalign as one of the line vertical spacing parameters +besides \baselineskip and \lineskip + I found this bug when having set globally \lineskiplimit to +-2dd and setting e.g. \d{a}. What a surprise -- the dot +wasn't there! Or what do you expect to see with simple +file saying +\lineskiplimit-2dd\d a\bye +? Dot below a or `in a'? + +Will I be sent a check? + +Petr Sojka <sojka@muni.cz> +------- +(reply, 12 Jan 1995) +yep, you're right. it's a bug. +the dot doesn't disappear, exactly, it just hides "in" the a. +\b b does kind of the same thing, but \c c is protected because +it uses \ooalign. + +yes, i think you'll get a check for this one, though i predict +it'll be just a small one, 'cuz the big ones only get awarded +for bugs in tex(.web) itself. +[ i didn't discover the earlier report until after i'd replied; + too bad. ] +------- + + ---------------------------------------------------------------------- + + +++ hyphenation inhibited by struts + +Date: 06 Jan 1994 12:04:38 +0100 +From: Piet van Oostrum <piet@cs.ruu.nl> +Subject: Bug in TeX + +Barbara, + +Could you forward the following to Knuth (I suppose you still act as a +forwarding agent). + +I consider the following a bug in TeX (in fact in the Plain macros): + +The first and last words in a footnote are never hyphenated. + +This is because plain TeX inserts struts, which are rules, and as these are +adjacent to the first and last words, they inhibit hyphenation. + +The solution is to insert \hskip0pt\relax between the struts and the text. +In fact I think it would be better to include this in the definition of +\strut. + +The solution to Exercise 22.8 has the same deficiency. + +Piet* van Oostrum, Dept of Computer Science, Utrecht University, +Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands. +------- +[ dek -- I believe it is also true that the first word of _any_ + paragraph is not hyphenated. (I prefer actually to + disable hyphens on the final word; but anyway this change + is far too drastic to be contemplated at this time.) +] +(reply, 06 Jan 1994) +piet, +thanks for your report. +i'll forward it to knuth, but i know his response: +this isn't a real bug; it's an unfortunate feature, and if he +had thought about it in 1984, he probably would have done what +you suggest. but tex/plain/etc. are now frozen, and he's not +going to make any changes except for indisputable bugs. + +he will probably also suggest that you write this up for tugboat. +so i will beat him to it -- would you write this up in a form +suitable for the "warnings" column? this would best take the +form of a brief, clear description (the description in your +message is certainly clear enough) with an example or two +showing "before" and "after". let me know what you think. +------- +Date: 07 Jan 1994 09:44:09 +0100 +From: Piet van Oostrum <piet@cs.ruu.nl> +Subject: Re: Bug in TeX + +>>>>> bbeeton <BNB@MATH.AMS.ORG> (BB) writes: + +BB> piet, +BB> thanks for your report. +BB> i'll forward it to knuth, but i know his response: [...] + +I'll just wait for DEK's response and then write a warning article about +it. Thanks for your effort. +------- +[ dek -- I certainly agree that he should make such a contribution to + _Warnings_. + NB. There is an \allowhyphens macro [in Appendix D, not in plain] +] + + ---------------------------------------------------------------------- + + +++ TeXbook, page 363, in \endinsert + +Date: 09 Feb 1994 12:29:08 +0100 (MET) +From: vieth@convex.rz.uni-duesseldorf.de (Ulrik Vieth) +Organization: Heinrich-Heine-Universitaet Duesseldorf +Subject: Re: for Knuth: minor typo in MFbook + +Hi Barbara, + +after I printed out all the errata files yesterday, I've checked it +again. Here is what I found out: + +[ this turned out to have been resolved, but i've left the comment + in the report for background. ] +The METAFONTbook, 5th printing, March 1990 is quite a strange mixture. +[ dek -- royal foulup in _many_ printings. Ask Phyllis for copies + of letters I wrote to A-W when i first noticed it ... +] +It does include the changes from errata.five (1989) and errata.six +until 3/13/90, excluding those dated 3/24/90 or later. It does *not* +include the changes from errata.three nor those from errata.four, +unless they happen to fall on pages affected by the later changes. +My conclusion that some of the changes from 3/87 were done, was just +a conincidence since most of them were index corrections on pages +that were changed again in 1989--1990. I'll try to locate a newer +printing of the METAFONTbook next week at the DANTE meeting to check +if they have been done in subsequent printings. However, I couldn't +find any note about the 6th printing in my copy of errata.three. +There seem to be different of that file around. + +[ this is the problem that still remains ... ] +OK, so far about the METAFONTbook. When I was at it, I also checked +my copy of the TeXbook, 18th printing, May 1990. Here, there were +no serious problems. It includes the changes from errata.six until +3/24/90, so it was completed sliightly later than the METAFONTbook, +5th printing. The only small problem I found was the change on page +A363, dated 8/12/89, that should have been in, but isn't. I'll try +[ dek -- he's correct ... this never made it into print. +] +to investigate this in a newer printing as well, but there might be +the odd chance that it came too late when the bunch of changes +dated 3/12/89 were send off and was forgotten with the next bunch +a few months later. In any case, I'll try to find out. + +Greetings, Ulrik Vieth. +------- + +i found this bug for page a363 in errata.six: + + \bugonpage A363, lines 8--9 from the bottom (12/8/89) + + {\ninepoint\parindent=0pt + | \if@mid \dimen@=\ht0 \advance\dimen@ by\dp\z@ |% + |\advance\dimen@ by12\p@|\parbreak% + | \advance\dimen@ by\pagetotal \advance\dimen@ by-\pageshrink| + \par} +[ dek * ] +------- +Date: 18 Feb 1994 18:23:06 +0100 (MET) +From: vieth@convex.rz.uni-duesseldorf.de (Ulrik Vieth) +Subject: Re: for Knuth: minor typo in MFbook + +Hi Barbara, + +I have just returned from the DANTE meeting, where I found a copy of +the 7th printing of the METAFONTbook to check. It appears to me that +the changes from errata.three and errata.four that were missing in +the 5th printing are finally in there. So the problem I reported is +mostly solved. + +About the TeXbook: I've noticed that the famous duplicated exercise bug +that was still present in the 22nd printing (final version) has been +corrected in the 23rd printing. However the change on page A363 (8/12/89) +is missing there as well. Of course it is in plain.tex 3.0 or later, but +apparently page A363 has not been updated in the 18th printing or any +other printing since then. So I guess this is indeed a problem for Knuth +and Addison-Wesley. Although my first problem has disappeared in the end, +this has led to the discovery of another problem still pending, so it +was worthwhile after all. +[ dek -- \check +] + +Ulrik Vieth. +------- + +<<< end plain.tex + +************************************************************************ + +>>> Metafont + + +++ arithmetic overflow with z=whatever[z',z''] + +Date: Mon, 9 May 94 14:44:46 WETDST +From: Tomek Przechlewski <tomasz@panda.bg.univ.gda.pl> +Subject: Bug in Metafont? + +Dear Barbara, + +I am passing the request of my friend Bogus{\l}aw +Jackowski (you have met him in Aston last year). He cannot find the +explanation of MF performance in the example appended below. + +Could you answer why in quite similar situations there are +so different outcomes. Is this a bug in Metafont or a feature? + +I look forward to hearing from you + +--Tomek Przechlewski + +% =================================================================== + +% +% \rm{}The following simple \MF\ program yielded unexpected (to me) results: +% +z1=whatever[(0,328),(100,329-eps)]; +z2=whatever[(0,328),(100,329)]; +z3=whatever[(0,328),(100,329+eps)]; +z4=whatever[(0,328),(100,329+2eps)]; +showdependencies; +end. +%%\def\~{\kern.15em} +% +% \rm{}The log file produced by, e.\~g., sbMF reads as follows: +% +% This is METAFONT, Version 2.71(c)sb13 (preloaded base=plain 93.5.6) +% 23 JUL 1993 17:22 +%%%% originally the ampersand was not preceded by the slash, of course +% ** \&plain aritover.mf +% (aritover.mf +% ! Arithmetic overflow. +% l.5 ...atever[(0,328),(100,329)] +% ; +% ? +% ! Arithmetic overflow. +% l.6 ...er[(0,328),(100,329+eps)] +% ; +% ? +% ! Arithmetic overflow. +% l.6 ...r[(0,328),(100,329+eps)]; +% +% ? +% y4=0.01001x4+328 +% y3=0.01001x3+327.83998 +% y2=0.01x2+327.68 +% y1=0.01x1+328 ) +% +% \rm{}Although Phil Taylor's opinion is that ``.\~.\~. the `bug' appears +% \rm{}to be a feature; the error message is well-defined, and `help' gives +% \rm{}a sensible diagnostic .\~.\~.'' I can hardly agree that this is OK. +% \rm{}Good luck to everybody using equations of the form |z=whatever[z',z'']|. +% +% \rm{}Bogus\l{}aw Jackowski +% \rm{}ul. Tatrza\'nska 6/1 +% \rm{}80-331 Gda\'nsk, Poland. +% +% +% \rm{}P.\~S. For the first time I came up against this situation on 4 III 1993 +% \rm{}(the equation was |z=whatever[(37.0092,419.22664),(280.3105,417.96634)]|). +% \rm{}Since that time I had ``a pleasure'' of encountering it several times. BJ. +%%\let\makefootline\empty\end +------- +Date: Tue, 17 May 94 12:46:02 WETDST +From: Tomek Przechlewski <tomasz@panda.bg.univ.gda.pl> +Subject: B. Jackowki's replay + +Dear Barbara, + +thank you for your responding to Tomek's mail. + +> ...there was another report about METAFONT arithmetic overflow just +> last week... + +Both error messages which are the subject of Pierre MacKay's response +have nothing to do with the METAFONT's behavior I had to struggle with: + +1. +> alpha=diag_ratio(4,stem2-stem3+stem4,y1-y2,x8r-x1l+mid_corr-2apex_corr); + +The `diag_ratio' macro does not make any use of `whatever[...]' construction, +while my troubles are strictly connected with this construction. + +2. +>z4=z5+whatever*(150u,h); + +Here the `! Arithmetic overflow' error occurs because the value of expression +`150u' is too large: for cminch font u=223.51988 at 2540 dpi, hence the +product would be about 33528, which is the number too large for METAFONT +(her actual infinity is 32767.99998). So, once again, `whatever[...]' +construction is not to blame. + +In my example I am using fairly ``regular'' numbers (ranging from zero to +about 300) and, moreover, the behavior of METAFONT seems to be numerically +instable, as changing the numbers by `eps' (in plain METAFONT eps=0.00049) +has apparent impact on `! Arithmetic overflow' error. + +Of course, I am not in a position to insist on prof. Knuth to change +METAFONT, neither I wish to overload him with unnecessary work. Nevertheless, +I would be happy to learn at least when such a situation may occur; then it +will perhaps become clear how to avoid it. + +Cheers. Jacko + +PS: and Tomek. +------- +[ message forwarded to chris thompson, but no response ] + + ---------------------------------------------------------------------- + + +++ several reports from Bogus{\l}aw Jackowski + +Date: 18 Oct 1994 16:06:45 +0100 (MET) +From: Wlodek Bzyl <matwb@halina.univ.gda.pl> +Subject: errors of TeX, MF (from B. Jackowski) + +Hi, Barbara, + +This file contains actually five different files put together to facilitate +electronic transmission and maintenance. Files are separated by `-=-=-= ...' +lines. All of them contain remarks concerning may-be-bugs in various +D. E. Kunth's products. If the authorship of a remark is not stated +explicitly, this means that it is mine (BJ's). + + Bogus\l{}aw Jackowski + ul. Tatrza\'nska 6/1 + 80-331 Gda\'nsk, Poland + + + SYNOPSIS + +1) File ARITOVER.MF: describes troubles with METAFONT's arithmetical overflow + in context of linear equations; I've already sent this file to you, + but for the completeness reason I put it along with other messages. + To see the problem you can compile the file with METAFONT and/or + to print it using MFT utility with PL.MFT data (enclosed separately). + + Perhaps Phil Taylor is right that what I regard as a bug is merely + a feature. If so, I would gladly learn how to avoid the problems + which this `feature' may cause. + +2) File SHUFFLED.TEX: discusses the problem of validity of the + ``shuffled binary property'' of METAFONT operation `intersectiontimes.' + This file can be compiled using TeX + MANMAC macros. + +3) File CSCSPU.CH: contains a minor change to the METAFONT sources + of the CM fonts. + +4) File ITALD.CH: contains a minor change to the METAFONT sources + of the CM fonts. + +5) File 2R1Q2TXB.TEX: contains two minor remarks (possibly out of date) + and one question concerning misprintings in The TeXbook. This file + can be compiled using TeX + MANMAC macros. + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% FILE ARITOVER.MF +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% +% \rm{}The following simple \MF\ program yielded unexpected (to me) results: +% +z1=whatever[(0,328),(100,329-eps)]; + +% [ text removed; complete message appears above ] +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% END OF FILE ARITOVER.MF +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% FILE SHUFFLED.TEX +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + +\let\MFmanual=\! +\input manmac \vsize24cm \pageheight\vsize +\def\rhead{Chapter 14. Paths} +\def\MFbook#1{% + {\def\MF{{\manual 89:;}\-{\manual <=>:\/}}% slant the logo + \sl The~\MF book#1}} +\pageno137 \proofmodefalse + +\vdots + +\bigskip + +[ dek -- p137 +] +\ddanger If the paths intersect more than once, \MF\ has a somewhat +peculiar way of deciding what times $(t,u)$ should be reported by +`$p$~intersectiontimes~$q$'. Suppose $p$ has length~$m$ and $q$ has +length~$n$. \ (Paths of length~0 are first changed into motionless paths +of length~1.) \ \MF\ proceeds to examine subpath~$(k,k+1)$ of~$p$ +versus subpath~$(l,l+1)$ of~$q$, for $k=0$, \dots,~$m-1$ and $l=0$, +\dots,~$n-1$, with $l$ varying most rapidly. This reduces the general +problem to the special case of paths of length~1, and the times $(t,u)$ +for the first such intersection found are added to $(k,l)$. But within +paths of length~1 the search for intersection times is somewhat +different: Instead of reporting the ``lexicographically smallest'' pair +$(t,u)$ that corresponds to an intersection, \MF\ finds the $(t,u)$ +whose ``^{shuffled binary}'' representation $(.t_1u_1t_2u_2\ldots\,)_2$ +is minimum, where $(.t_1t_2\ldots\,)_2$ and $(.u_1u_2\ldots\,)_2$ are +the radix-2 representations of $t$ and~$u$. + +\bigskip + +\vdots + +\bigskip + +\tenpoint + +This is what \MFbook\/ says on page 137. Then follows Exercise 14.17 which +makes use of the ``shuffled binary property.'' Alas, the ``shuffled binary +property'' does not hold. Consider a path $p=(a,b)\dashto(c,d)$. One would +expect that the result of `$p$~\null intersectiontimes~\null reverse~$p$' +should be $(0,1)$, as the shuffled binary representation is for this case +$(.01010\ldots\,)_2$ which is the {\it minimum\/} of the shuffled binary +representations for pairs $(x,1-x)$, ${0\le x\le1}$. + +Indeed, most likely the result will be like that (sometimes within some +accuracy). But if there exist \MF\ numbers $c'$~and~$d'$ such that +$c$~and~$d$ are of the form ${c=a+3c'}$ and ${d=a+3d'}$, the result is +[ dek -- ^ b +] +astonishingly~$(0.5,0.5)$. This apparently contradicts the quoted statement +as the shuffled binary representation of $(0.5,0.5)$ is $(.11)_2$ which is +the {\it maximum\/} of the shuffled binary representations for pairs +$(x,1-x)$, ${0\le x\le1}$. + +Here you have a little \MF\ program which can produce arbitrarily many +`|>>|~|(0.5,0.5)|' messages on your terminal: + + \begintt + path p; numeric a,b,c,d,n; n:=10; + for i:=1 upto n: + a:=uniformdeviate 1000; b:=uniformdeviate 1000; + c:=a+3uniformdeviate 1000; d:=b+3uniformdeviate 1000; + p:=(a,b)--(c,d); + show p intersectiontimes reverse p; + endfor + \endtt + +\medskip + +My basic question is: does the above specification cover all exceptions +from the shuffled binary property? + +Also, I wonder whether it is a ``white lie,'' or a mistake in \MFbook, +or---God forbid!---a bug in \MF\kern.1em? + +[ dek -- ANSWER: + This is an interesting question (but you could have figured it + out from the program. I admit that the documentation is ``terse'', + but the algorithm is pretty enough to reward a close look.) + In fact we _do_ get the minimum shuffled binary, which happens + to be not .0101010101... but .001111111111... [even smaller!]; + which gives (0.5,0.5). + The point .001111111111 seems to lie on both curves only when + there is absolutely no truncation error, and I believe this + happens if and only if the control points z_0 .. controls z, + and z_2 .. z_3 satisfy z_1 - z_0 = z_2 - z_1 = z_3 - z_2 . + Otherwise it's necessary to go to the next higher case. + Of course the intersection point routine is not intended for + such curves -- it is supposed to -|- find genuine crossing points. +] + +\bigskip + +\rightline{\vbox{\halign{#\hss\cr +\it June 10, 1994\cr +\noalign{\medskip} +Bogus\l{}aw Jackowski\cr +ul. Tatrza\'nska 6/1\cr +80-331 Gda¤sk\cr +Poland\cr +}}} + +\end + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% END OF FILE SHUFFLED.TEX +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% FILE CSCSPU.CH +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + +% Following a change in ROMANU.MF I would suggest a similar change +% in CSCSPU.MF: +% +@x +bulb(3,4,5); % bulb +@y +[ dek -- $2.56 +] +pickup tiny.nib; bulb(3,4,5); % bulb +@z +% +% The original version of CSCSPU generates bad ``dotless'' small cap `j' +% in Computer Concrete CCCSC10 font. + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% END OF FILE CSCSPU.CH +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% FILE ITALD.CH +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + +% The non-zero depth of the italic digit seven was noticed by 12 years old +% Joanna Ry\'cko. I cannot see any reason for keeping this state of the art. +% It seems that the following change in ITALD.MF would be appropriate: +@x +beginchar("7",9u#,fig_height#,desc_depth#); +@y +beginchar("7",9u#,fig_height#,0); +@z + +[ dek -- I have sworn not to change the TFM files ever again. So this + curious glitch is permanent. (Long ago _all_ italic digits had + the same descender. Later I corrected everything but the 7; + we can live with it. +] + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% END OF FILE ITALD.CH +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% FILE 2R1Q2TXB.TEX +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= + +\input manmac \vsize24cm \pageheight\vsize +\proofmodefalse +\def\rhead{} +\def\rightheadline{} +\font\bsl cmbxsl10 + +\centerline{\bf Two Remarks and One Question} +\centerline{\bf Concerning \bsl The \TeX book} + +\bigskip + +% [ this one has been fixed ] +1)\enspace Noticed by Marek Ry\'cko: In the eighteenth printing of {\sl The +\TeX book\/} Exercise~8.7 appears twice (one after the other). + +\bigskip + +2)\enspace Noticed by Marek Ry\'cko: In the source of {\sl The \TeX book\/} +(incorporating the final corrections made in 1993) on the page~31 a space +precedes improperly the word `\TeX' just after the verbatim quotation: +[ dek -- $2.56 +] + +\medskip + +\noindent `[\dots] after typing something like this: +\begintt +! Undefined control sequence. +l.2 \vship + 1in +? +\endtt +\def\storypage{24} % listing of story.tex +\TeX\ begins its error messages with `|!|', and it shows what it was +reading at the time of the error by displaying two lines of context~[\dots]' + +\medskip + +\tolerance1000 +The reason for this is that after the verbatim quotation there is a command +|\def\storypage{24}|, and there is a space after it. +[ dek -- ^^^^^^ This command is in fact redundant -- I moved it to + manmac.tex but forgot to delete it from texbook.tex +] + +\bigskip + +3)\enspace The ``problem'' raised during the Euro\TeX'94 meeting in Gda\'nsk, +Poland: What is the proper spelling of Addison$\,*\,$Wesley: Addison-Wesley +(back of the cover of {\sl The \TeX book}, prepared probably by the +publisher) or Addison Wesley (the~source of {\sl The \TeX book\/}), or both? + +[ dek -- They flip-flopped several times during the 80s, as they had + different chief graphic designers for their ``corporate image''. + I couldn't keep up. +] + +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +% END OF FILE 2R1Q2TXB.TEX +%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= +------- + +<<< end Metafont + +************************************************************************ + +>>> CM fonts + + +++ missing "cmchar"s in bigdel.mf + +Date: Sat, 07 Mar 92 15:23:59 GMT +From: Chris Thompson <CET1@phoenix.cambridge.ac.uk> +Cc: REH10@phoenix.cambridge.ac.uk +Subject: Missing "cmchar"s in bigdel.mf + +Barbara, + +[ dek -- E95,E97 $2.56 +] +Robert Hunt (reh10@phx.cam.ac.uk) has pointed out that in bigdel.mf +the expected "cmchar"s on line 596 (character `077) and line 645 +(character `167) are missing. (As "cmchar" is usually a no-op, this +only matters if you are trying to play the sort of games described +on pp.312-313 of the METAFONTbook.) It seems to be just an oversight: +perhaps you can add it to DEK's list? + +Chris Thompson +JANET: cet1@uk.ac.cam.phx +------- + + ---------------------------------------------------------------------- + + +++ shaved_stem vs. cap_stem in greeku.mf + +Date: 14 May 1993 17:38:30 -0300 (BST) +From: Chris Thompson <CET1@phx.cam.ac.uk> +To: Barbara Beeton <BNB@MATH.AMS.ORG> +Cc: Robert Hunt <REH10@phx.cam.ac.uk> +Subject: Re: [Minor CM fonts bug] + +Barbara, + +Robert Hunt reports the following: +> Line 196 of greeku.mf, which currently reads +[ dek -- E187,E189 $2.56 +] +> +> lft x1l=lft x2l=hround(.5w-.5cap_stem); top y1=h; bot y2=0; +> +> should read +> +> lft x1l=lft x2l=hround(.5w-.5shaved_stem); top y1=h; bot y2=0; +> +> Exactly the same bug also occurs on line 215. (These are in the +[ dek -- ^^^ 216 +] +> character programs for capital Phi and Psi respectively.) + +This looks right to me: at some stage 'shaved_stem' was introduced +to these programs instead of 'cap_stem', but these two occurrences +were missed. + +Chris Thompson +Cambridge University Computing Service +------- + + ---------------------------------------------------------------------- + + +++ miscellanea from Robert Hunt, mostly in CM sources + +Date: 29 Mar 1994 21:01:42 -0300 (BST) +From: Robert Hunt <REH10@phx.cam.ac.uk> +Cc: Chris Thompson <CET1@phx.cam.ac.uk> +Subject: TeX bugs + +Dear Barbara, + +I've been saving up several bugs I've found in the Computer Modern sources, the +METAFONTbook and Plain TeX for quite a while, and am now sending them on to you +for DEK. Perhaps you could add them to his list of things to look at next time +he reviews TeX etc. - I fully realise that this probably won't be for some +quite considerable time! +[ dek - ^^^^^^^^^^^^^^^ ^^^^ +] + +This message is, I'm afraid, rather long, but I thought it'd be better to send +you everything in one go rather than split it up into lots of separate +messages. Each of the bugs is separated by a line of ------'s below. +[ dek -- well done +] + +Thanks & best wishes, +Robert Hunt. + + ------------------------------------------------------------------------------ + +There seems to be a recurrent error in the code for the various Computer Modern +[ dek -- OK on pE481 +] +integral signs. For example, in the code for the \displaystyle integral sign in +bigop.mf, the line + lft x5r=hround(.5w-.5stem); +[ dek -- E113, E115 $2.56 + four places in bigop.mf + " " " ebigop.mf +] +should actually read + lft x5r=hround(.5w-.5max_size); +as the character is max_size pixels wide at z5. (In fact, the stem parameter +does not feature in the program for this character in any other way!) Similar +comments apply to all the other sizes and styles of integral signs. + + ------------------------------------------------------------------------------ + +In the code for the Computer Modern partial differential sign in italms.mf, the +line + path p; p=pulled_super_arc.l(3,4)(pull); +[ dek -- E233 $2.56 +] +should be replaced by + path p; {{interim superness:=more_super; p=pulled_super_arc.l(3,4)(pull)}}; + + ------------------------------------------------------------------------------ + +In symbol.mf, the code for the Computer Modern elementary division operator has +a bug causing the dots to be drawn with diameter dot_size+rule_thickness rather +than dot_size. (It's clear that they're meant to be of diameter dot_size +[ dek -- ^^^^^ No, the dots are the correct size but the + defs of x_3,y_3 are inappropriate + E438 $2.56 +] +because of the definition of x3.) The reason that the code doesn't work is that +pos doesn't know the breadth of rule.nib, so doesn't subtract anything off from +[ dek -- currentbreadth is in fact set from the pickup fine.nib of the + integral sigh (by chance) -- I should make my intentions clear, + without changing the character image that I got by luck. +] +dot_size. Various fixes are possible (such as changing the font_setup routine +in cmbase.mf to define breadth_[rule.nib]=rule_thickness), but the simplest +seems to be to insert a line saying "pickup fine.nib;" just after the draw +command. + + ------------------------------------------------------------------------------ + +There seems to be an error in the syntax definition for <path expression> on +page 213 of the METAFONTbook (and also in the simplified definition on page +129). I hope that I haven't embarrassed myself by misunderstanding it! + +The syntax as given doesn't seem to allow "(0,0)..(1,0)" as a +<path expression>. A <path join> (".." here, with empty direction specifiers) +must be followed by either "cycle" or <path tertiary>. A <path tertiary> must +start with a <path primary>. But "(1,0)" cannot be a <path primary>, as it is +[ dek -- C129 $2.56 +] +not a <path argument> or <path variable>, nor is it "(<path expression>)" +(since "1,0" without the brackets is not a valid <path expression>). +[ dek -- <pair tertiary< movves from subexpr level to tertiary level +] + + ------------------------------------------------------------------------------ + +There is a low-resolution anomaly that arises in the Computer Modern equals +sign and several other such characters. Each of the bars of "=" is meant to be +drawn by an identical _circular_ pen. However, at low resolutions (e.g., +300dpi, with mode CanonCX) the character can often turn out looking like the +following: + + xxxxxxxxxxxx + xxxxxxxxxxxxxx + + xxxxxxxxxxxxxx + xxxxxxxxxxxx + +which doesn't have the symmetry one would expect at the end-points of the +lines. This is due to the way in which the heights of the two bars are chosen; +the centre-points of the bars are at heights math_axis+.5spread and +math_axis-.5spread. Now math_axis has been chosen to be a good.y position for +rule.nib, and spread has been chosen to be an integer+eps; but this means that +if spread is an _odd_ integer (+eps) then the edges of the nib when it draws +the two bars are at almost exactly the _least_ optimal heights for drawing! +(I.e., an integer+.5+1/2eps.) This results in a loss of vertical symmetry at +the end-points of each bar. + +My suggested solution for this is to ensure that spread is always an even +integer (apart from the correction of size eps), as follows: + def compute_spread(expr normal_spread,big_spread)= + spread#:=math_spread[normal_spread,big_spread]; + spread:=2ceiling(spread#*hppp/2)+2eps; enddef; +[ dek -- E491 $2.56 ^ I left this out. _I_ _don't_ _know_ + _why_, but it caused the equal isgn to look like + xxx---x + xx---x + + xx---x + xxx---x + quite asymmetric! + I don't have time to fool around, but I guess this definition + is an improvement even though the 2eps should've been + good too ... + +0 OK + +eps OK + +2eps NG + +3eps NG + +1/3 NG +] +This does have the disadvantage that at very low resolutions characters can end +up being rather widely spread. + + ------------------------------------------------------------------------------ + +The character "H" in font cmssdc10, at pixels_per_inch=300 and mag=magstep1 +(the other parameters are unimportant), demonstrates a rounding problem which +is in fact present in a very great number of the Computer Modern character +definitions. At the top and bottom left of the left-hand stem, a pixel has been +cut out; but on the right of the left-hand stem, and on both sides of the +right-hand stem, these pixels are filled in. This makes the character very +asymmetric. + +The problem is caused because the stem is drawn with a pen of non-zero +thickness which is turning a corner, and because of a nicety which is discussed +in the METAFONTbook on the top of page 200. Basically, the line + lft x1l=lft x2l=hround max(2u,3u-.5cap_stem); x3=x4=w-x1; +in the definition of "H" in romanu.mf should be replaced by the two lines + lft x1l=lft x2l=hround max(2u,3u-.5cap_stem)-eps; + rt x3r=rt x4r=w-hround max(2u,3u-.5cap_stem); +(or something equivalent to these two). We want to avoid the vertices of the +"tiny" pen polygon (which is being used to draw the character) passing through +any ambiguous points whenever it turns a corner, and to do that we want its +centre to lie at a half-integer minus eps whenever it's at the left-hand side +of a stroke region, and at a half-integer (exactly) when it's at the right-hand +side of a stroke. (By "half-integer" here I mean either an integer or an +integer plus 1/2, dependent on the breadth of the "tiny" nib.) Since the "pos" +command of cmbase sets the distance between x$l and x$r to be an integer plus +eps (because the breadth of the tiny pen is set to an integer minus eps by the +font_setup routine), the command "lft x1l=hround(...)-eps" sets lft x1l to an +integer minus eps and rt x1r to exactly an integer; whereas "rt +x3r=hround(...)" sets rt x3r to an integer and lft x3l to an integer minus eps. +These commands therefore ensure that the stroke will have left-right symmetry. + +So the general rule which seems to be required is that in many of the CM +programs, + lft x$l=hround(...); +should be replaced by + lft x$l=hround(...)-eps; +whereas + rt x$r=hround(...); +should be left alone. Unfortunately this isn't a hard-and-fast rule, so would +be difficult to do automatically; in particular, commands such as + lft x$l=w-rt x$$r=hround(...); +need to be split into two statements. + +In fact, even the METAFONT logo font itself is subject to this problem! The "F" +character in logo.mf can suffer from asymmetry of the top bar, with pixels +being lost at the left-hand side (the right-hand side being alright). A quick +solution would seem to be to set leftstemloc to an integer minus eps instead of +exactly an integer, but I haven't checked this carefully to make sure it would +work correctly. + +Is it worth doing anything about this? It's a very minor problem, and to put it +[ dek -- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + To raise this question is to answer it! +] +right would require an awful lot of changes to the Computer Modern source +files. Unless some super-whazzo solution involving changing the "lft" macro +(etc.) can be thought up, it would be a very large amount of work. + + ------------------------------------------------------------------------------ + +There are a number of infelicities and/or bugs in the Plain TeX format. I've +listed some I know about below in approximately decreasing order of importance; +some (especially near the end of the list) are a little esoteric. + +% The Plain TeX \skew macro does not work properly with variable-size accents +% such as \widetilde. The following rewrite corrects that. +[ dek -- And makes people wonder why divide by 2 instead of using half + the skew originally! +] +% +\def\skew#1#2#3{{\muskip\z@#1mu\divide\muskip\z@\tw@ \mkern\muskip\z@ + #2{\mkern-\muskip\z@{#3}\mkern\muskip\z@}\mkern-\muskip\z@}{}} +[ dek -- p359 $2.56 +] +% +% The maths spacing inserted by \bmod is incorrect in script or scriptscript +% styles, because \nonscript was not used. +% +\def\bmod{\nonscript\mskip-\medmuskip\mkern5mu + \mathbin{\rm mod}\penalty900\mkern5mu\nonscript\mskip-\medmuskip} +[ dek -- p361 $2.56 + I hope this won't mess up too many people who have already + compensated for this bug. +] +% +% \displaylines does not work correctly if \tabskip happens to be non-zero when +% it is called (for instance, if the user does an \halign of his own with a +% non-zero \tabskip, just before using $$\displaylines{...}$$). +% +\def\displaylines#1{\displ@y \tabskip\z@skip + \halign{\hbox to\displaywidth{$\@lign\hfil\displaystyle##\hfil$}\crcr + #1\crcr}} +[ dek -- p362 $2.56 +] +% +% If a maths display is started when \prevdepth=-1000pt, the \openup adjustment +% which \displ@y automatically inserts before the first line of the display to +% compensate for the change in the value of \baselineskip should be omitted. +% +\def\displ@y{\global\dt@ptrue\openup\jot\m@th + \everycr{\noalign{\ifdt@p \global\dt@pfalse \ifdim\prevdepth>-1000\p@ + \vskip-\lineskiplimit \vskip\normallineskiplimit \fi + \else \penalty\interdisplaylinepenalty \fi}}} +[ dek -- p362 $2.56 + It is _very_ hard to reach this situation! + \noindent $$ \displaylines ... seems to be the simplese. +] +% +% [ \d{} and \b{} were reported earlier; see above under >>> plain.tex; +% this is the first report of \@vereq, i believe ] +% The \d and \b accent macros don't work if the user has set \lineskiplimit to +% a negative value, say around -2pt or less. The \@vereq macro (used only by +[ dek -- esplicitly ^ +] +% \cong) suffers from a similar problem. +% +\def\d#1{{\lineskiplimit\maxdimen\oalign{#1\crcr\hidewidth.\hidewidth}}} +\def\b#1{{\lineskiplimit\maxdimen\oalign{#1\crcr + \hidewidth\vbox to.2ex{\hbox{\char22}\vss}\hidewidth}}} +\def\@vereq#1#2{\lower.5\p@\vbox{\lineskiplimit\maxdimen\lineskip-.5\p@ + \ialign{$\m@th#1\hfil##\hfil$\crcr#2\crcr=\crcr}}} +[ dek -- p360 $2.56 +] +% +% Several definitions in Plain TeX contain excess tokens (typically redundant +% "=" signs, "by" keywords, etc.). Some (e.g. \m@th) are executed so frequently +% that it's worth removing them, which the following definitions do. +% +% [ removed ] +% +% [ removed some suggested hyphenations +% +% [ removed some suggested enhancements to operators like \sin ] +% +% \settabs breaks spectacularly in the (somewhat unlikely) eventuality of it +[ dek -- ^^^^^^^^^^^^^ agreed +] +% being followed by an \if; for example, +% \settabs \ifdim\hsize<8in 3 \else 4 \fi\columns +[ dek -- p354 $2.56 +] +% +\let\temp=\+ \let\+=\relax + +\def\sett@b{\ifx\next\+\def\nxt{\afterassignment\s@tt@b\let\nxt}% + \else\let\nxt\s@tcols\fi \let\next\relax \nxt} +\def\s@tt@b{\let\nxt\relax\us@false\m@ketabbox} + +\let\+=\temp +% +% English authors would greatly prefer to use English spellings in their +% command names! +% +% [ removed ] + + ------------------------------------------------------------------------------ + +[ additional bugs summarized; separate reports included above ] +------- +(reply, 29 Mar 1994) +robert, +thanks very much for your collection. + +a comment on plain.tex. knuth has communicated to me that he +will never again change plain.tex ; here is his response to a +suggestion sent to him in february 1993: + + [ dek: These macros look very good but I cannot change plain TeX + any more at this late date. _Ever_._ + (Wish I had thought of them in 1985!) + He should publish them in TUGboat. + ] + +presumably if there is a very bad and obscure bug *that doesn't +take effect very often* he might consider making an exception, +but his ideal now is that the entire tex system remain stable, +permanently. his recommendation that remaining problems, and +suggested improvements, be published in tugboat must be taken +at face value. if i don't pay attention to such comments, and +send in everything that's sent to me, i put myself in danger +of incurring his severe displeasure, which would jeopardize my +welcome to forward real bugs. if you really do want to submit +these suggestions for plain.tex to him, you should do it yourself +by regular post. his address is + + Prof. Donald E. Knuth + Department of Computer Science + Stanford University + Stanford, CA 94305 U.S.A. + +you could mention that i wouldn't forward them, or not, as you +wish. (i'll let you know what i do forward when i next put a +package together; that should be within the coming month.) + +regarding the computer modern sources, he may feel the same way +as about plain.tex, but it's never been tested. +------- +Date: 11 Apr 1994 21:42:27 -0300 (BST) +From: Robert Hunt <REH10@phx.cam.ac.uk> +To: bbeeton <BNB@MATH.AMS.ORG>, Chris Thompson <CET1@phx.cam.ac.uk> +Subject: Re: TeX bugs + +Dear Barbara, + +Thanks for your message about my bug collection. I understand DEK's position on +Plain TeX, that he doesn't want to change it any more, and will certainly +respect that. (Though I suppose I would be grateful if when you forward the +rest of my list to him, you would just add a one-liner saying that there used +to be several Plain TeX bug-fixes there but that you've removed them with my +co-operation for this very reason!) + +How would I go about publishing them in TUGboat? [...] +------- + +[ dek -- Barbara, I relented this time only because his macros were elegant + and instructive and (with the exception of \bmod) unlikely to + make existing .tex files obsolete. + The \bmod bug is something I'm sure people have compensated for, + e.g., by inserting a thin space where it now will look better + without any such manual tuning up ... + but I decided the correction desirable anyway. + + For example, I had to change the MS to Concrete Math in seven places. + We could tell people to put the old def of \bmod in their files + if they don't wish to change. (That's what I decided to do with + Concrete Math.) + + I do expect to be EXTREMELY hardnosed about ANY future changes + to plain.tex, however. My thought is that this might as well be + the one last chance for changes -- since \d was so badly in need + of correction (four separate changes to it!) + Therefore, _please_ _keep_ telling people so exactly what you have + been telling them so kindly about the frozen-ness of plain.tex. +] + + ---------------------------------------------------------------------- + + +++ cap_ess in cmmi12 and larger + +Date: 01 Feb 1994 18:17:07 +0100 +Reply-to: METAFONT Distribution List <metafont@ens.fr> +From: KNAPPEN@VKPMZD.kph.Uni-Mainz.DE +Subject: c-cmmi.mf (Sauter tools) revisited: Bug in cap_ess +[ dek -- ^^^^^^^^^^^^ This is something I have nothing to do with... +] + +Bug report in c-cmmi.mf + +At 17.28pt the middle part of the letter S in cmmi looks too thin. I have +gone into the parameters and found the following formula for +cap_ess (design_size>10, rest omitted): + +cap_ess#:=(-design_size*5 + 380)/360 pt#; + +this means that the parameter cap_ess# decreases with design_size and will +reach zero at 76 pt! So why that decrease? Let's look at the Knuthian +parameters for cmr, cmmi and cmti: + +font 5 6 7 8 9 10 12 (pt#) +cmr 14 19 23 27 31 35 43 (1/36 pt#) +cmmi 13.5 18.5 22.5 26 30 33 32 +cmti -- -- 21 24 27 31 34 + +For all font but cmmi12, cap_ess of cmmi is between the values of cmr and +cmti, but closer to the cmr value. It look as if for cmmi12 a value of 42 +was aimed at, but for some reasons 32 has become a feature of this font. If +you look sharply at the S in cmmi12 (at 600dpi), you might find it a little +too light besides the letter R, but this is at the edge of visibility (at +least for my eye), therefore I'd never noticed it without looking at the +parameters. +[ dek -- As far as I know, there was no good formula for the ess widths; + I just played until they seemed right -- I defer to committee for + these things. +] + +However, further decrease of cap_ess is a bad idea, it should increase +again from design_size=12 on. + +Here a proposed formula for design_size>12, it yields 320/360 pt# at +12 and increases then, never getting bigger then the cmr-value: + +(design_size*9 + 216) / 360pt# + +It will be, however, lower then the value of cap_ess in cmti. +Since roman letters may appear in matematical formulae, the alignment +to the cmr parameters is imho the more important case. + +Fortunately, a change in the parameter cap_ess does not affect the font +metrics (or have I missed something?), therefore we can make a change here +[ dek -- ^^^^^^^^^ true -- anybody can change to + heart's content +] +without disturbing documents using the Sauter fonts. + +Comments? + +Yours, J"org Knappen. +------- + + ---------------------------------------------------------------------- + + +++ possible glitch in cmbx5 and cmbx6 + +Date: 15 Dec 1994 12:01:51 -0800 (PST) +From: kinch@netcom.com (Richard J. Kinch) +To: tex-implementors@MATH.AMS.ORG +Subject: Bug in cmbx5 and cmbx6 + +I believe there is a latent bug in Computer Modern cmbx5 and cmbx6. + +The meta-ness seems to degenerate at the 5-point optical size used in cmbx5. +For example, digit "7" grows a wart on top, and serifs on glyphs like A, K, M, +N, U, V, W, X, Y, and others are notched in the inside corners. The "7" +problem is clearly visible at 300 dpi when magnified to cmbx5 at 37.15pt. The +serif notching is not evident except at even larger magnifications. At normal +size at 300 or 600 this is not necessarily visible. + +In C&T Volume E (Computer Modern Typefaces) on page 560 there is a sample of +cmbx5. Under a 10x lens or so you can see extra ink on the top of the +digit "7". I believe there is a one- or two-pixel wart on top of "7" in the +cmbx6 sample, too. + +The problems are evident in proof-size printouts. + +I discovered this in converting the METAFONT shapes to Bezier outlines with my +automatic converter, METAFOG. I saw the misshapen glyphs and puzzled for days +thinking I had a bug in my converter. + +Richard Kinch +------- + +[ dek -- It's okay to change the shapes of CM fonts as long as you don't + change the TFM files. I haven't time to fix this problem + since I don't consider enlarged cmbx an important font ... + I was unable to see the notches on the A, but I agree that the 7 + [drawn outline of 7, with a lump on the top] looks cancerous. + Not a problem at the sizes intended. Ultrabold is where + meta-ness can be expected to break first. + + (Congrats on METAFOG) +] + + ---------------------------------------------------------------------- + + +++ arithmetic overflow in CMinch + +Date: 05 May 1994 14:08:55 -0700 +From: mackay@cs.washington.edu (Pierre MacKay) +To: BNB@MATH.AMS.ORG +Cc: Bob@microprograms.com, mackay@cs.washington.edu, unixtex@u.washington.edu +Subject: Arithmetic overflow in CMinch + +Bob Harris (bob@microprograms.com) got in touch with me a couple +of days ago to report that it was not popssible to run +cminch with a 2540dpi LinotypeThreeZeroZero mode_def. + +The letter W and the numeral 3 generate the +! Arithmetic overflow +message, and the problem is far too serious to +be turned off with warningcheck:=0; +even if you wanted to do that. + +The offending lines were easy enough to spot: + in romanu.mf one third of the way through "The letter W" +[ dek -- E291 32\cents +] + +alpha=diag_ratio(4,stem2-stem3+stem4,y1-y2,x8r-x1l+mid_corr-2apex_corr); + + in romand.mf. halfway through "The numeral 3" + +z4=z5+whatever*(150u,h); + +Fortunately both of these statements generate ratios, so that the +raw arguments can be reduced consistently with no change in the results. +I extract from my email messages, slightly edited. + + > Think of "whatever" (in this manifestation) + > as a path of infinite length along the angle + > specified by (150u,h) + > Since the angle (15u,0.1h) is exactly the same + > ---I checked it with expr.mf, and there is no + > loss of precision---there is the answer. + > Write the offending line as + +z4=z5+whatever*(15u,0.1h); + + > The same trick that works for 3 works for W, though it requires a + > little more editing. + +alpha=diag_ratio(4,.1(stem2-stem3+stem4), + .1(y1-y2),.1(x8r-x1l+mid_corr-2apex_corr); +[ dek -- This doesn't fit on page E113 and besides it is too kludgy -- + bad style ... + What I shall really do is redefine diag_ratio -- it's pointless + to multiply by y and divide by y again! + + > This has the effect of calculating on a dpi measure of 254, but since what + > we are looking for is a ratio, it makes no difference. I ran with + > both calculations using the ljfour mode (effectively that means one + > calculation at 600dpi and one at 60dpi) and got exactly the same ratio + + > There is a small rounding difference in the 2540dpi file + + > 600dpi gives a diag_ratio of 1.03595 + > 2540 dpi gives a diag_ratio of 1.03609 + + > That may well be an artifact of some decisions in the parameter file. + > I doubt that .00014 is enough to worry about in this context. + > (The ratio that results after the ! arithmetic overflow is, of course, + > grossly out of line. + +I was a bit puzzled at first to explain why this hadn't showed up before, +since I have made up fonts at 9600dpi and even 14454dpi, but the answer +lies in the peculiarity of a 72.27pt font. Even a 17pt parameter file +has to be run at magstep 3 before its em-square reaches 1000 pixels in +width at 2540dpi. But there could be real problems with cmr17 at the +9600dpi that Lance Carnes uses to derive his Chelgraph outlines from. + +I wonder if DEK would be interested in preempting this problem, since +the solution is so painless, and will not affect TFM checksums. +------- + + ---------------------------------------------------------------------- + + +++ sterling sign + +Date: 04 Jan 1995 00:29:37 +0100 +Reply-to: METAFONT Distribution List <metafont@ens.fr> +From: Yannis Haralambous <Yannis.Haralambous@univ-lille1.fr> +Subject: error in CM fonts + +IMHO the following error has to be corrected: + +In file italp.mf, character "Sterling sign", line -7, replace +rt x9r=hround(w-u); +[ dek -- E239 $2.56 +] +by +rt x9l=hround(w-u); +Otherwise the results are bad in typewriter style and catastrophic in +sans-serif. The funny thing is that I could _swear_ that on the image +of the character the code is correct [probably a typo by Addison-Wesley]. + +Yannis +------- +Date: 04 Jan 1995 10:35:54 +0100 +Reply-to: METAFONT Distribution List <metafont@ens.fr> +From: Piet van Oostrum <piet@cs.ruu.nl> +Subject: Re: error in CM fonts + +>>>>> Yannis Haralambous <Yannis.Haralambous@univ-lille1.fr> (YH) writes: + +YH> IMHO the following error has to be corrected: + +YH> In file italp.mf, character "Sterling sign", line -7, replace +YH> rt x9r=hround(w-u); +YH> by +YH> rt x9l=hround(w-u); +YH> Otherwise the results are bad in typewriter style and catastrophic in +YH> sans-serif. The funny thing is that I could _swear_ that on the image +YH> of the character the code is correct [probably a typo by Addison-Wesley]. + +It can't be a typo by Addison Wesley, because it is in Knuth's original +sources (AW didn't type, they got -- of course -- the source from Knuth). + +If you look at the image you can really see that it is generated by the x9r +code, because the character sticks out a little bit to the right of the +x=11 line. Notice that the x9r point is to the LEFT of the x9l point!! + +And yes, with your correction it looks much better in sans serif. In the +[ dek -- ^^^^^^^^^^ + what sans serif?? This char does not have a sans serif style + in the present design ... sans serif has no ``bulbs'' +] +italic font, which is the only cm font where it is used, the difference +[ dek -- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +] +isn't very great because the x9r and x9l point are quite close top each +other, whereas in the sans-serif case they are 1 u apart. + -- +Piet van Oostrum <piet@cs.ruu.nl> +------- + +<<< end CM fonts + +************************************************************************ + +>>> Fontware + + +++ testfont.tex + +X-ListName: TeX-Related Network Discussion List <INFO-TeX@SHSU.edu> +Date: 05 Feb 1993 20:44 +0000 (GMT) +From: J%org Knappen <KNAPPEN@VKPMZD.KPH.Uni-Mainz.de> +Subject: Bug in testfont.tex + +By chance I came across to notice a feature of testfont.tex, which I regard +as a bug: + +In the \lowers and \uppers test, the kerning and ligature information is +not used. Therefore it is not possible to adjust the spacing of a font +using this tool. Since I know that some experts in macro expansion are +aroung here, i think one of them will take the challenge to rewrite +the routines of testfont.tex in order to be completely expandable and use +the kerning. + +Yours, J"org Knappen. +------- + +[ dek -- Font designers traditionally test without kerning (at least + they did when I worked with them in 80-85), but I suppose + such macros would be easy to write. +] + + ---------------------------------------------------------------------- + + +++ VPtoVF + +Date: 23 Aug 1993 10:08:20 +0200 +From: Armin.Koellner@RUBA.RZ.ruhr-uni-bochum.de +Subject: VPtoVF bug report and some comments on the AMS fonts + +Dear Barbara Beeton, + +since you stated in one of your letters that you are the right person +to get in contact with D.E.Knuth, I am sending to you a report of a +bug in the web file VPtoVF (Version 1.2, 90/9/5) which I found when +experimenting with ligature tables generated by a program written by +myself: + +If a ligature table erroneously starts with a STOP command, VPtoVF +will often destroy other data. This abnormal behaviour appears +because the variable lk_step_ended is not initialized by program code +to be FALSE, so that the conduct of the program depends on the random +contents of the memory cell the variable inherits. I suggest to +change the web file in order to correct this bug. + +Additionally, I would like to suggest some improvements on the AMS +symbol fonts, and, as you are working for the AMS (I suppose), could +you please give it to the font developer of your organisation? Thank +you very much. + +When I experimented with a program which handles fonts by detecting +their font coding scheme, I got stuck with the AMS symbol font series +msam and msbm. At first I detected that in my version of these fonts +(version="2.1a", date="15-OCT-1991") the series msbm* had no font +coding scheme string at all! This happened because the file xbbold.mf +ends with the token "end" instead of giving the control back to the +file amsyb.mf which ends correctly with "bye". I think, this bug +should be corrected. +[ this bug was fixed shortly after receiving this report ] + +Secondly, the AMS symbol fonts have the same font coding scheme +string as the cmsy* series, namely "TeX math symbols". This makes +them indistinguishable when considering only this string. As far as +[ dek -- not really needed for msam -- only for fonts used in + family 2, 3 ... +] +I understand, this special name is necessary for programs like TFtoPL +and VFtoVP to handle the character coding and math symbol font +parameters correctly. However, by reading the corresponding web files +for these programs, I learned that they only consider the first 11 +characters of the font coding scheme string. Therefore, I suggest for +the next version of your font series to name the font coding scheme +"TeX math symbols by AMS, Part A" and "TeX math symbols by AMS, +Part B", resp. +[ dek -- good suggestion +] + +Yours sincerely, +Armin K\"ollner +------- +Date: 26 Aug 1993 12:54:58 -0300 (BST) +From: Chris Thompson <CET1@phx.cam.ac.uk> +Subject: Re: [[Armin.Keollner: VPtoVF bug report and some comments]] + +Barbara, + +Armin Kollner writes: +> If a ligature table erroneously starts with a STOP command, VPtoVF + (or a SKIP command) +> will often destroy other data. This abnormal behaviour appears +> because the variable lk_step_ended is not initialized by program code +> to be FALSE, so that the conduct of the program depends on the random +> contents of the memory cell the variable inherits. I suggest to +> change the web file in order to correct this bug. + +This is indeed a bug in the current versions of VPtoVF and PLtoTF. +I found it rather difficult to demonstrate, as the uninitialised +variable ends up as binary zero (typically = Pascal "false") on +most systems. I did manage it eventually, though. + +[...] + +> Secondly, the AMS symbol fonts have the same font coding scheme +> string as the cmsy* series, namely "TeX math symbols". This makes +> them indistinguishable when considering only this string. As far as +> I understand, this special name is necessary for programs like TFtoPL +> and VFtoVP to handle the character coding and math symbol font +> parameters correctly. However, by reading the corresponding web files +> for these programs, I learned that they only consider the first 11 +> characters of the font coding scheme string. Therefore, I suggest for +> the next version of your font series to name the font coding scheme +> "TeX math symbols by AMS, Part A" and "TeX math symbols by AMS, +> Part B", resp. + +It is true that PLtoTF and VPtoTF (currently!) test only the initial +section of the coding scheme ("TEX MATH SY" or "TEX MATH EX", after +upper casing) when setting |font_type|. The result is used to control +the format used in the (V)PL output for various things (whether to +use names or numbers for the higher-numbered FONTDIMENs, and whether +to use D or C format for certain character numbers). This only affects +human-readability, though: the semantic content is not affected. + +Quite how the "font coding scheme" should be used is far from obvious, +but it is certainly arguable that the msam*/msbm* fonts do not have +the same "coding scheme" as the cmsy* fonts, in the sense that +characters at corresponding code positions are not, in any plausible +sense the "same" meta-character. I don't know whether a change could +really be said to make "use of these files ... more reliable" (to +quote you), though. + +[...] + +Chris Thompson +Cambridge University Computing Service +------- + +<<< end Fontware + +************************************************************************ |