summaryrefslogtreecommitdiff
path: root/Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c
diff options
context:
space:
mode:
Diffstat (limited to 'Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c')
-rw-r--r--Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c121
1 files changed, 121 insertions, 0 deletions
diff --git a/Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c b/Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c
new file mode 100644
index 00000000000..4f11bbe0c78
--- /dev/null
+++ b/Build/source/utils/pmx/pmx-2.6.18/libf2c/z_log.c
@@ -0,0 +1,121 @@
+#include "f2c.h"
+
+#ifdef KR_headers
+double log(), f__cabs(), atan2();
+#define ANSI(x) ()
+#else
+#define ANSI(x) x
+#undef abs
+#include "math.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+extern double f__cabs(double, double);
+#endif
+
+#ifndef NO_DOUBLE_EXTENDED
+#ifndef GCC_COMPARE_BUG_FIXED
+#ifndef Pre20000310
+#ifdef Comment
+Some versions of gcc, such as 2.95.3 and 3.0.4, are buggy under -O2 or -O3:
+on IA32 (Intel 80x87) systems, they may do comparisons on values computed
+in extended-precision registers. This can lead to the test "s > s0" that
+was used below being carried out incorrectly. The fix below cannot be
+spoiled by overzealous optimization, since the compiler cannot know
+whether gcc_bug_bypass_diff_F2C will be nonzero. (We expect it always
+to be zero. The weird name is unlikely to collide with anything.)
+
+An example (provided by Ulrich Jakobus) where the bug fix matters is
+
+ double complex a, b
+ a = (.1099557428756427618354862829619, .9857360542953131909982289471372)
+ b = log(a)
+
+An alternative to the fix below would be to use 53-bit rounding precision,
+but the means of specifying this 80x87 feature are highly unportable.
+#endif /*Comment*/
+#define BYPASS_GCC_COMPARE_BUG
+double (*gcc_bug_bypass_diff_F2C) ANSI((double*,double*));
+ static double
+#ifdef KR_headers
+diff1(a,b) double *a, *b;
+#else
+diff1(double *a, double *b)
+#endif
+{ return *a - *b; }
+#endif /*Pre20000310*/
+#endif /*GCC_COMPARE_BUG_FIXED*/
+#endif /*NO_DOUBLE_EXTENDED*/
+
+#ifdef KR_headers
+VOID z_log(r, z) doublecomplex *r, *z;
+#else
+void z_log(doublecomplex *r, doublecomplex *z)
+#endif
+{
+ double s, s0, t, t2, u, v;
+ double zi = z->i, zr = z->r;
+#ifdef BYPASS_GCC_COMPARE_BUG
+ double (*diff) ANSI((double*,double*));
+#endif
+
+ r->i = atan2(zi, zr);
+#ifdef Pre20000310
+ r->r = log( f__cabs( zr, zi ) );
+#else
+ if (zi < 0)
+ zi = -zi;
+ if (zr < 0)
+ zr = -zr;
+ if (zr < zi) {
+ t = zi;
+ zi = zr;
+ zr = t;
+ }
+ t = zi/zr;
+ s = zr * sqrt(1 + t*t);
+ /* now s = f__cabs(zi,zr), and zr = |zr| >= |zi| = zi */
+ if ((t = s - 1) < 0)
+ t = -t;
+ if (t > .01)
+ r->r = log(s);
+ else {
+
+#ifdef Comment
+
+ log(1+x) = x - x^2/2 + x^3/3 - x^4/4 + - ...
+
+ = x(1 - x/2 + x^2/3 -+...)
+
+ [sqrt(y^2 + z^2) - 1] * [sqrt(y^2 + z^2) + 1] = y^2 + z^2 - 1, so
+
+ sqrt(y^2 + z^2) - 1 = (y^2 + z^2 - 1) / [sqrt(y^2 + z^2) + 1]
+
+#endif /*Comment*/
+
+#ifdef BYPASS_GCC_COMPARE_BUG
+ if (!(diff = gcc_bug_bypass_diff_F2C))
+ diff = diff1;
+#endif
+ t = ((zr*zr - 1.) + zi*zi) / (s + 1);
+ t2 = t*t;
+ s = 1. - 0.5*t;
+ u = v = 1;
+ do {
+ s0 = s;
+ u *= t2;
+ v += 2;
+ s += u/v - t*u/(v+1);
+ }
+#ifdef BYPASS_GCC_COMPARE_BUG
+ while(s - s0 > 1e-18 || (*diff)(&s,&s0) > 0.);
+#else
+ while(s > s0);
+#endif
+ r->r = s*t;
+ }
+#endif
+ }
+#ifdef __cplusplus
+}
+#endif