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diff --git a/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Adobe-Garamond-Pro-example.tex b/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Adobe-Garamond-Pro-example.tex new file mode 100644 index 00000000000..28ce36780c8 --- /dev/null +++ b/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Adobe-Garamond-Pro-example.tex @@ -0,0 +1,271 @@ +\documentclass[12pt]{article} + +\usepackage[T1]{fontenc} +\usepackage[latin1]{inputenc} +% \usepackage[french]{babel} +\usepackage{amsmath} +\usepackage{amsthm} +%\usepackage{mathrsfs} +\newtheorem{theorem}{Theorem}[section] +\newtheorem{definition}{Definition}[section] +\newenvironment{demo}{\noindent {\bf Dem.}}{\qed} +\newenvironment{remarque}{\noindent {\bf Rem.} \small \itshape}{} +\newenvironment{exemple}{\noindent {\bf Example}}{} + +\newcommand{\Lu}{L^1(\Rset)} +\newcommand{\tf}[1]{{\cal F}\left(#1\right)} +\newcommand{\ii}{{\mathrm{i}}} +\newcommand{\Cn}{{\cal C}^{n}} +\newcommand{\dd}{\mathrm{d}} +% ;; \newcommand{\Rset}{{\mathbb R}} +\newcommand{\Rset}{R} +\newcommand{\R}{\mathbb R} +\newcommand{\C}{\mathbb R} +\newcommand{\ex}{\mathrm{e}} +\newcommand{\Cinf}{{\cal C}^{\infty}} +\newcommand{\abs}[1]{\left| #1 \right|} +\newcommand{\dx}{\dd x} +\newcommand{\ds}{\displaystyle} +\newcommand{\vect}[1]{\overrightarrow{#1}} +\newcommand{\Boule}[2]{\mathscr B(#1,#2)} +\newcommand{\Cercle}[2]{\mathscr C(#1,#2)} +\DeclareMathOperator{\Arg}{Arg} + +\newcommand{\dep}[2]{\ds \frac{\partial #1}{\partial #2}} + +\title{Example of the \textsf{mdpgd} fonts.} + +\author{Paul Pichaureau} + + +\usepackage[cal=scr,mdpgd,greekfamily = didot]{mathdesign} +%% \usepackage{amssymb} + +\begin{document} + +\maketitle + +\begin{abstract} + The package \textsf{mdpgd} consists of a full set of + mathematical fonts, designed to be combined with Adobe + Adobe Garamond Pro as the main text font. + + This example is extracted from the excellent book {\em + Mathematics for Physics and Physicists}, {\sc W. Appel}, + Princeton University Press, {\sc 2007}. + +\end{abstract} + + +\section{Conformal maps} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\subsection{Preliminaries} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +Consider a change of variable $(x,y)\mapsto +(u,v)=\big(u(x,y),v(x,y)\big)$ in the plane $\R^2$, identified +with~$\C$. This change of variable really only deserves the name if +$f$ is locally bijective (i.e., one-to-one); this is the case if the +jacobian of the map is nonzero (then so is the jacobian of the +inverse map): +\begin{equation*} + \left| \frac{{D}(u,v)}{{D}(x,y)}\right| = + \begin{vmatrix} + \ds\frac{\displaystyle\partial u}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial u}{\displaystyle\partial y} \\[4mm] + \ds\frac{\displaystyle\partial v}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial v}{\displaystyle\partial y} + \end{vmatrix}\neq 0 + \qquad\text{and}\qquad + \left| \frac{{D}(x,y)}{{D}(u,v)}\right| + =\begin{vmatrix}\ds\dep{x}{u} &\ds \dep{x}{v}\\[4mm] + \ds\dep{y}{u} &\ds \dep{y}{v} + \end{vmatrix}\neq 0. +\end{equation*} +\begin{theorem} +In a complex change of variable +\begin{equation*} + z= x+\ii y\longmapsto w=f(z)=u+\ii v, +\end{equation*} +and \emph{if $f$ is holomorphic}, then the jacobian of the map is equal to +\begin{equation*} + J_f(z)=\left| \frac{{D}(u,v)}{{D}(x,y)}\right|= + \abs{f'(z)}^2. +\end{equation*} +\end{theorem} +\begin{demo} + Indeed, we have $f'(z)=\dep{u}{x}+\ii\dep{v}{x}$ and hence, by the + Cauchy-Riemann relations, + \begin{align*} + \abs{f'(z)}^2 & = + \left(\dep{u}{x}\right)^2+\left(\dep{v}{x}\right)^2 + = + \dep{u}{x}\dep{v}{y}-\dep{v}{x}\dep{u}{y}=J_f(z). + \end{align*} +\end{demo} + +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal map} or \emph{conformal transformation} of an + open subset $\Omega\subset\R^2$ into another open subset + $\Omega'\subset\R^2$ is any map $f:\Omega\mapsto \Omega'$, locally + bijective, that preserves angles and orientation. +\end{definition} + +\begin{theorem} + Any conformal map is given by a holomorphic function $f$ such + that the derivative of $f$ does not vanish. +\end{theorem} + +This justifies the next definition: +%% ---------------------------------------------------------------------- +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal transformation} or \emph{conformal map} of + an open subset + $\Omega\subset\C$ into another open subset + $\Omega'\subset\C$ is any holomorphic function + $f:\Omega\mapsto \Omega'$ such that + $f'(z)\neq 0$ for all $z\in\Omega$. +\end{definition} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{demo}[that the definitions are equivalent] + We will denote in general $w=f(z)$. Consider, in the complex plane, two + line segments $\gamma_1$ and $\gamma_2$ contained inside the set $\Omega$ + where $f$ is defined, and intersecting at a point $z_0$ in $\Omega$. + Denote by $\gamma'_1$ and $\gamma_2'$ their images by~$f$. + + We want to show that if the angle between $\gamma_1$ and $\gamma_2$ is + equal to $\theta$, then the same holds for their images, which means that + the angle between the tangent lines to $\gamma'_1$ and $\gamma'_2$ at + $w_0=f(z_0)$ is also equal to $\theta$. + + Consider a point $z\in\gamma_1$ close to~$z_0$. Its image $w=f(z)$ + satisfies + \begin{equation*} + \lim_{z\to z_0} \frac{w-w_0}{z-z_0}=f'(z_0), + \end{equation*} + and hence + $$\displaystyle \lim_{z\to z_0} \Arg + (w-w_0)-\Arg(z-z_0) = \Arg f'(z_0), $$% + which shows that the angle between the curve $\gamma'_1$ and the real + axis is equal to the angle between the original segment $\gamma_1$ and + the real axis, plus the angle $\alpha=\Arg f'(z_0)$ (which is well + defined because $f'(z)\neq 0$). + + Similarly, the angle between the image curve $\gamma'_2$ and the real + axis is equal to that between the segment $\gamma_2$ and the real axis, + plus the same~$\alpha$. + + Therefore, the angle between the two image curves is the same as that + between the two line segments, namely, $\theta$. + + Another way to see this is as follows: the tangent vectors of the curves + are transformed according to the rule $\vect{V}'=\dd f_{z_0}\vect{V}$. But the + differential of $f$ (when $f$ is seen as a map from $\R^2$ to~$\R^2$) is + of the form + \begin{equation} + \displaystyle \dd f_{z_0}=\begin{pmatrix} + \displaystyle \dep{P}{x} & \displaystyle \dep{P}{y} \\[4mm] + \displaystyle \dep{Q}{x} & \displaystyle \dep{Q}{y}\end{pmatrix} + = + \abs{f'(z_0)}\begin{pmatrix}\cos\alpha& -\sin\alpha + \\ \sin\alpha &\cos\alpha \end{pmatrix}, + \label{eq:FSimil} + \end{equation} + where $\alpha$ is the argument of $f'(z_0)$. This is the matrix of a + rotation composed with a homothety, that is, a similitude. + + \medskip +%% ······································································ + % {\begin{picture}(300,100) + % \put(0,0){\epsfig{file=\Figures/TC.\Ext,height=3.2cm}} + % \put(20,65){$\gamma_2$} \put(80,55){$\theta$} + % \put(100,80){$\gamma_1$} \put(195,85){$\gamma'_1$} + % \put(245,35){$\theta$} \put(270,60){$\gamma'_2$} + % \end{picture}} +%% ······································································ + + Conversely, if $f$ is a map which is $\R^2$-differentiable and preserves + angles, then at any point $\dd f$ is an endomorphism of~$\R^2$ which + preserves angles. Since $f$ also preserves orientation, its determinant + is positive, so $\dd f$ is a similitude, and its matrix is exactly + as in equation~\eqref{eq:FSimil}. The Cauchy-Riemann equations are + immediate consequences. +\end{demo} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{remarque} + \index{Antiholomorphic function}% + \index{Function!antiholomorphic ---}% + An \emph{antiholomorphic} map also preserves angles, but it + reverses the orientation. +\end{remarque} +%% ---------------------------------------------------------------------- + +\newpage +\subsection*{Calcul différentiel} + + + +Pour obtenir la différentielle totale de cette expression, considérée comme fonction de $x$, $y$, ..., donnons à $x$, $y$, ... des accroissements $d\!x$, $d\!y$, .... Soient $\Delta u$, $\Delta v$, ..., $\Delta f$ les accroissements correspondants de $u$, $v$, ...,$f$. On aura +\begin{equation*} + \Delta f= \dfrac{\partial\! f}{\partial u} \Delta u + \dfrac{\partial\! f}{\partial v} \Delta v + \hdots + R\Delta u + R_1 \Delta v + \hdots, +\end{equation*} +$R$, $R_1$, ... tendant vers zéro avec $\Delta u$, $\Delta v$, .... + +Mais on a, d'autre part, +\begin{align*} + \Delta u & = \dfrac{\partial u}{\partial x} d\! x + + \dfrac{\partial u}{\partial y} \Delta y + \hdots + S\Delta x + S_1 \Delta y + \hdots \\ +& = du + Sd\! x + S_1 d\! y + \hdots \\ + \Delta v & = \dfrac{\partial v}{\partial x} d\! x + + \dfrac{\partial v}{\partial y} \Delta y + \hdots + T\Delta x + T_1 \Delta y + \hdots \\ +& = dv + Td\! x + T_1 d\! y + \hdots \\ +\hdots +\end{align*} +$S$, $S_1$, ..., $T$, $T_1$,... tendant vers zéro avec $d\! x$, $d\! y$, .... + +Substituant ces valeurs dans l'expression de $\Delta f$, il vient +\begin{equation*} +\begin{array}{rcl} + \vbox to 25pt {} \Delta f & = &\dfrac{\partial\! f}{\partial u} d u + \dfrac{\partial\! f}{\partial v} d v + \hdots + \rho d\! x + \rho_1 d\! y + \hdots \\ +\vbox to 25pt {}& = & \phantom{+} \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots \right) d\! x \\ +\vbox to 25pt {}& & + \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots \right) d\! y \\ +\vbox to 25pt {}&& + \hdots + \rho d\! x + \rho_1 d\! y + \hdots +\end{array} +\end{equation*} +$\rho$, $\rho_1$, ... tendant vers zéro avec $d\! x$, $d\! y$, .... + +On aura donc +\begin{align*} + \dfrac{\partial\! f}{\partial x}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots, \\ + \dfrac{\partial\! f}{\partial y}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots, \\ +\hdots +\end{align*} +et, d'autre part, +\begin{equation*} + df = \dfrac{\partial\! f}{\partial u} {\mathrm d} u + \dfrac{\partial\! f}{\partial v} {\mathrm d} v + \hdots ; +\end{equation*} +d'où les deux propositions suivantes : + +{\em La dérivée, par rapport à une variable indépendante $x$, d'une fonction composée $f(u,v,\hdots)$ s'obtient en ajoutant ensemble les dérivées partielles $\dfrac{\partial\! f}{\partial u}$, $\dfrac{\partial\! f}{\partial v}$, ..., respectivement multipliées par les dérivées de $u$, $v$, ... par rapport à $x$. + +La différentielle totale $df$ s'exprimer au moyen de $u$, $v$, ..., $du$, $dv$, ..., de la même manière que si $u$, $v$, ... étaient des variables indépendantes. +} + +\hbox to \textwidth { \hfill + {\sc Camille Jordan}, {\em Cours d'analyse de l'\'Ecole polytechnique} +} + +\end{document} diff --git a/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Utopia-Std-example.tex b/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Utopia-Std-example.tex new file mode 100644 index 00000000000..76fa5730d3d --- /dev/null +++ b/Master/texmf-dist/doc/fonts/mathdesign/MD-Adobe-Utopia-Std-example.tex @@ -0,0 +1,271 @@ +\documentclass[12pt]{article} + +\usepackage[T1]{fontenc} +\usepackage[latin1]{inputenc} +% \usepackage[french]{babel} +\usepackage{amsmath} +\usepackage{amsthm} +%\usepackage{mathrsfs} +\newtheorem{theorem}{Theorem}[section] +\newtheorem{definition}{Definition}[section] +\newenvironment{demo}{\noindent {\bf Dem.}}{\qed} +\newenvironment{remarque}{\noindent {\bf Rem.} \small \itshape}{} +\newenvironment{exemple}{\noindent {\bf Example}}{} + +\newcommand{\Lu}{L^1(\Rset)} +\newcommand{\tf}[1]{{\cal F}\left(#1\right)} +\newcommand{\ii}{{\mathrm{i}}} +\newcommand{\Cn}{{\cal C}^{n}} +\newcommand{\dd}{\mathrm{d}} +% ;; \newcommand{\Rset}{{\mathbb R}} +\newcommand{\Rset}{R} +\newcommand{\R}{\mathbb R} +\newcommand{\C}{\mathbb R} +\newcommand{\ex}{\mathrm{e}} +\newcommand{\Cinf}{{\cal C}^{\infty}} +\newcommand{\abs}[1]{\left| #1 \right|} +\newcommand{\dx}{\dd x} +\newcommand{\ds}{\displaystyle} +\newcommand{\vect}[1]{\overrightarrow{#1}} +\newcommand{\Boule}[2]{\mathscr B(#1,#2)} +\newcommand{\Cercle}[2]{\mathscr C(#1,#2)} +\DeclareMathOperator{\Arg}{Arg} + +\newcommand{\dep}[2]{\ds \frac{\partial #1}{\partial #2}} + +\title{Example of the \textsf{mdpus} fonts.} + +\author{Paul Pichaureau} + + +\usepackage[cal=scr,mdpus,greekfamily = didot]{mathdesign} +%% \usepackage{amssymb} + +\begin{document} + +\maketitle + +\begin{abstract} + The package \textsf{mdpus} consists of a full set of + mathematical fonts, designed to be combined with Adobe + Utopia Std as the main text font. + + This example is extracted from the excellent book {\em + Mathematics for Physics and Physicists}, {\sc W. Appel}, + Princeton University Press, {\sc 2007}. + +\end{abstract} + + +\section{Conformal maps} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\subsection{Preliminaries} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +Consider a change of variable $(x,y)\mapsto +(u,v)=\big(u(x,y),v(x,y)\big)$ in the plane $\R^2$, identified +with~$\C$. This change of variable really only deserves the name if +$f$ is locally bijective (i.e., one-to-one); this is the case if the +jacobian of the map is nonzero (then so is the jacobian of the +inverse map): +\begin{equation*} + \left| \frac{{D}(u,v)}{{D}(x,y)}\right| = + \begin{vmatrix} + \ds\frac{\displaystyle\partial u}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial u}{\displaystyle\partial y} \\[4mm] + \ds\frac{\displaystyle\partial v}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial v}{\displaystyle\partial y} + \end{vmatrix}\neq 0 + \qquad\text{and}\qquad + \left| \frac{{D}(x,y)}{{D}(u,v)}\right| + =\begin{vmatrix}\ds\dep{x}{u} &\ds \dep{x}{v}\\[4mm] + \ds\dep{y}{u} &\ds \dep{y}{v} + \end{vmatrix}\neq 0. +\end{equation*} +\begin{theorem} +In a complex change of variable +\begin{equation*} + z= x+\ii y\longmapsto w=f(z)=u+\ii v, +\end{equation*} +and \emph{if $f$ is holomorphic}, then the jacobian of the map is equal to +\begin{equation*} + J_f(z)=\left| \frac{{D}(u,v)}{{D}(x,y)}\right|= + \abs{f'(z)}^2. +\end{equation*} +\end{theorem} +\begin{demo} + Indeed, we have $f'(z)=\dep{u}{x}+\ii\dep{v}{x}$ and hence, by the + Cauchy-Riemann relations, + \begin{align*} + \abs{f'(z)}^2 & = + \left(\dep{u}{x}\right)^2+\left(\dep{v}{x}\right)^2 + = + \dep{u}{x}\dep{v}{y}-\dep{v}{x}\dep{u}{y}=J_f(z). + \end{align*} +\end{demo} + +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal map} or \emph{conformal transformation} of an + open subset $\Omega\subset\R^2$ into another open subset + $\Omega'\subset\R^2$ is any map $f:\Omega\mapsto \Omega'$, locally + bijective, that preserves angles and orientation. +\end{definition} + +\begin{theorem} + Any conformal map is given by a holomorphic function $f$ such + that the derivative of $f$ does not vanish. +\end{theorem} + +This justifies the next definition: +%% ---------------------------------------------------------------------- +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal transformation} or \emph{conformal map} of + an open subset + $\Omega\subset\C$ into another open subset + $\Omega'\subset\C$ is any holomorphic function + $f:\Omega\mapsto \Omega'$ such that + $f'(z)\neq 0$ for all $z\in\Omega$. +\end{definition} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{demo}[that the definitions are equivalent] + We will denote in general $w=f(z)$. Consider, in the complex plane, two + line segments $\gamma_1$ and $\gamma_2$ contained inside the set $\Omega$ + where $f$ is defined, and intersecting at a point $z_0$ in $\Omega$. + Denote by $\gamma'_1$ and $\gamma_2'$ their images by~$f$. + + We want to show that if the angle between $\gamma_1$ and $\gamma_2$ is + equal to $\theta$, then the same holds for their images, which means that + the angle between the tangent lines to $\gamma'_1$ and $\gamma'_2$ at + $w_0=f(z_0)$ is also equal to $\theta$. + + Consider a point $z\in\gamma_1$ close to~$z_0$. Its image $w=f(z)$ + satisfies + \begin{equation*} + \lim_{z\to z_0} \frac{w-w_0}{z-z_0}=f'(z_0), + \end{equation*} + and hence + $$\displaystyle \lim_{z\to z_0} \Arg + (w-w_0)-\Arg(z-z_0) = \Arg f'(z_0), $$% + which shows that the angle between the curve $\gamma'_1$ and the real + axis is equal to the angle between the original segment $\gamma_1$ and + the real axis, plus the angle $\alpha=\Arg f'(z_0)$ (which is well + defined because $f'(z)\neq 0$). + + Similarly, the angle between the image curve $\gamma'_2$ and the real + axis is equal to that between the segment $\gamma_2$ and the real axis, + plus the same~$\alpha$. + + Therefore, the angle between the two image curves is the same as that + between the two line segments, namely, $\theta$. + + Another way to see this is as follows: the tangent vectors of the curves + are transformed according to the rule $\vect{V}'=\dd f_{z_0}\vect{V}$. But the + differential of $f$ (when $f$ is seen as a map from $\R^2$ to~$\R^2$) is + of the form + \begin{equation} + \displaystyle \dd f_{z_0}=\begin{pmatrix} + \displaystyle \dep{P}{x} & \displaystyle \dep{P}{y} \\[4mm] + \displaystyle \dep{Q}{x} & \displaystyle \dep{Q}{y}\end{pmatrix} + = + \abs{f'(z_0)}\begin{pmatrix}\cos\alpha& -\sin\alpha + \\ \sin\alpha &\cos\alpha \end{pmatrix}, + \label{eq:FSimil} + \end{equation} + where $\alpha$ is the argument of $f'(z_0)$. This is the matrix of a + rotation composed with a homothety, that is, a similitude. + + \medskip +%% ······································································ + % {\begin{picture}(300,100) + % \put(0,0){\epsfig{file=\Figures/TC.\Ext,height=3.2cm}} + % \put(20,65){$\gamma_2$} \put(80,55){$\theta$} + % \put(100,80){$\gamma_1$} \put(195,85){$\gamma'_1$} + % \put(245,35){$\theta$} \put(270,60){$\gamma'_2$} + % \end{picture}} +%% ······································································ + + Conversely, if $f$ is a map which is $\R^2$-differentiable and preserves + angles, then at any point $\dd f$ is an endomorphism of~$\R^2$ which + preserves angles. Since $f$ also preserves orientation, its determinant + is positive, so $\dd f$ is a similitude, and its matrix is exactly + as in equation~\eqref{eq:FSimil}. The Cauchy-Riemann equations are + immediate consequences. +\end{demo} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{remarque} + \index{Antiholomorphic function}% + \index{Function!antiholomorphic ---}% + An \emph{antiholomorphic} map also preserves angles, but it + reverses the orientation. +\end{remarque} +%% ---------------------------------------------------------------------- + +\newpage +\subsection*{Calcul différentiel} + + + +Pour obtenir la différentielle totale de cette expression, considérée comme fonction de $x$, $y$, ..., donnons à $x$, $y$, ... des accroissements $d\!x$, $d\!y$, .... Soient $\Delta u$, $\Delta v$, ..., $\Delta f$ les accroissements correspondants de $u$, $v$, ...,$f$. On aura +\begin{equation*} + \Delta f= \dfrac{\partial\! f}{\partial u} \Delta u + \dfrac{\partial\! f}{\partial v} \Delta v + \hdots + R\Delta u + R_1 \Delta v + \hdots, +\end{equation*} +$R$, $R_1$, ... tendant vers zéro avec $\Delta u$, $\Delta v$, .... + +Mais on a, d'autre part, +\begin{align*} + \Delta u & = \dfrac{\partial u}{\partial x} d\! x + + \dfrac{\partial u}{\partial y} \Delta y + \hdots + S\Delta x + S_1 \Delta y + \hdots \\ +& = du + Sd\! x + S_1 d\! y + \hdots \\ + \Delta v & = \dfrac{\partial v}{\partial x} d\! x + + \dfrac{\partial v}{\partial y} \Delta y + \hdots + T\Delta x + T_1 \Delta y + \hdots \\ +& = dv + Td\! x + T_1 d\! y + \hdots \\ +\hdots +\end{align*} +$S$, $S_1$, ..., $T$, $T_1$,... tendant vers zéro avec $d\! x$, $d\! y$, .... + +Substituant ces valeurs dans l'expression de $\Delta f$, il vient +\begin{equation*} +\begin{array}{rcl} + \vbox to 25pt {} \Delta f & = &\dfrac{\partial\! f}{\partial u} d u + \dfrac{\partial\! f}{\partial v} d v + \hdots + \rho d\! x + \rho_1 d\! y + \hdots \\ +\vbox to 25pt {}& = & \phantom{+} \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots \right) d\! x \\ +\vbox to 25pt {}& & + \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots \right) d\! y \\ +\vbox to 25pt {}&& + \hdots + \rho d\! x + \rho_1 d\! y + \hdots +\end{array} +\end{equation*} +$\rho$, $\rho_1$, ... tendant vers zéro avec $d\! x$, $d\! y$, .... + +On aura donc +\begin{align*} + \dfrac{\partial\! f}{\partial x}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots, \\ + \dfrac{\partial\! f}{\partial y}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots, \\ +\hdots +\end{align*} +et, d'autre part, +\begin{equation*} + df = \dfrac{\partial\! f}{\partial u} {\mathrm d} u + \dfrac{\partial\! f}{\partial v} {\mathrm d} v + \hdots ; +\end{equation*} +d'où les deux propositions suivantes : + +{\em La dérivée, par rapport à une variable indépendante $x$, d'une fonction composée $f(u,v,\hdots)$ s'obtient en ajoutant ensemble les dérivées partielles $\dfrac{\partial\! f}{\partial u}$, $\dfrac{\partial\! f}{\partial v}$, ..., respectivement multipliées par les dérivées de $u$, $v$, ... par rapport à $x$. + +La différentielle totale $df$ s'exprimer au moyen de $u$, $v$, ..., $du$, $dv$, ..., de la même manière que si $u$, $v$, ... étaient des variables indépendantes. +} + +\hbox to \textwidth { \hfill + {\sc Camille Jordan}, {\em Cours d'analyse de l'\'Ecole polytechnique} +} + +\end{document} diff --git a/Master/texmf-dist/doc/fonts/mathdesign/MD-itc-Charter-ITC-Std-example.tex b/Master/texmf-dist/doc/fonts/mathdesign/MD-itc-Charter-ITC-Std-example.tex new file mode 100644 index 00000000000..e24b3e0e511 --- /dev/null +++ b/Master/texmf-dist/doc/fonts/mathdesign/MD-itc-Charter-ITC-Std-example.tex @@ -0,0 +1,271 @@ +\documentclass[12pt]{article} + +\usepackage[T1]{fontenc} +\usepackage[latin1]{inputenc} +% \usepackage[french]{babel} +\usepackage{amsmath} +\usepackage{amsthm} +%\usepackage{mathrsfs} +\newtheorem{theorem}{Theorem}[section] +\newtheorem{definition}{Definition}[section] +\newenvironment{demo}{\noindent {\bf Dem.}}{\qed} +\newenvironment{remarque}{\noindent {\bf Rem.} \small \itshape}{} +\newenvironment{exemple}{\noindent {\bf Example}}{} + +\newcommand{\Lu}{L^1(\Rset)} +\newcommand{\tf}[1]{{\cal F}\left(#1\right)} +\newcommand{\ii}{{\mathrm{i}}} +\newcommand{\Cn}{{\cal C}^{n}} +\newcommand{\dd}{\mathrm{d}} +% ;; \newcommand{\Rset}{{\mathbb R}} +\newcommand{\Rset}{R} +\newcommand{\R}{\mathbb R} +\newcommand{\C}{\mathbb R} +\newcommand{\ex}{\mathrm{e}} +\newcommand{\Cinf}{{\cal C}^{\infty}} +\newcommand{\abs}[1]{\left| #1 \right|} +\newcommand{\dx}{\dd x} +\newcommand{\ds}{\displaystyle} +\newcommand{\vect}[1]{\overrightarrow{#1}} +\newcommand{\Boule}[2]{\mathscr B(#1,#2)} +\newcommand{\Cercle}[2]{\mathscr C(#1,#2)} +\DeclareMathOperator{\Arg}{Arg} + +\newcommand{\dep}[2]{\ds \frac{\partial #1}{\partial #2}} + +\title{Example of the \textsf{mdici} fonts.} + +\author{Paul Pichaureau} + + +\usepackage[cal=scr,mdici,greekfamily = didot]{mathdesign} +%% \usepackage{amssymb} + +\begin{document} + +\maketitle + +\begin{abstract} + The package \textsf{mdici} consists of a full set of + mathematical fonts, designed to be combined with Itc + Charter Itc Std as the main text font. + + This example is extracted from the excellent book {\em + Mathematics for Physics and Physicists}, {\sc W. Appel}, + Princeton University Press, {\sc 2007}. + +\end{abstract} + + +\section{Conformal maps} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\subsection{Preliminaries} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +Consider a change of variable $(x,y)\mapsto +(u,v)=\big(u(x,y),v(x,y)\big)$ in the plane $\R^2$, identified +with~$\C$. This change of variable really only deserves the name if +$f$ is locally bijective (i.e., one-to-one); this is the case if the +jacobian of the map is nonzero (then so is the jacobian of the +inverse map): +\begin{equation*} + \left| \frac{{D}(u,v)}{{D}(x,y)}\right| = + \begin{vmatrix} + \ds\frac{\displaystyle\partial u}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial u}{\displaystyle\partial y} \\[4mm] + \ds\frac{\displaystyle\partial v}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial v}{\displaystyle\partial y} + \end{vmatrix}\neq 0 + \qquad\text{and}\qquad + \left| \frac{{D}(x,y)}{{D}(u,v)}\right| + =\begin{vmatrix}\ds\dep{x}{u} &\ds \dep{x}{v}\\[4mm] + \ds\dep{y}{u} &\ds \dep{y}{v} + \end{vmatrix}\neq 0. +\end{equation*} +\begin{theorem} +In a complex change of variable +\begin{equation*} + z= x+\ii y\longmapsto w=f(z)=u+\ii v, +\end{equation*} +and \emph{if $f$ is holomorphic}, then the jacobian of the map is equal to +\begin{equation*} + J_f(z)=\left| \frac{{D}(u,v)}{{D}(x,y)}\right|= + \abs{f'(z)}^2. +\end{equation*} +\end{theorem} +\begin{demo} + Indeed, we have $f'(z)=\dep{u}{x}+\ii\dep{v}{x}$ and hence, by the + Cauchy-Riemann relations, + \begin{align*} + \abs{f'(z)}^2 & = + \left(\dep{u}{x}\right)^2+\left(\dep{v}{x}\right)^2 + = + \dep{u}{x}\dep{v}{y}-\dep{v}{x}\dep{u}{y}=J_f(z). + \end{align*} +\end{demo} + +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal map} or \emph{conformal transformation} of an + open subset $\Omega\subset\R^2$ into another open subset + $\Omega'\subset\R^2$ is any map $f:\Omega\mapsto \Omega'$, locally + bijective, that preserves angles and orientation. +\end{definition} + +\begin{theorem} + Any conformal map is given by a holomorphic function $f$ such + that the derivative of $f$ does not vanish. +\end{theorem} + +This justifies the next definition: +%% ---------------------------------------------------------------------- +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal transformation} or \emph{conformal map} of + an open subset + $\Omega\subset\C$ into another open subset + $\Omega'\subset\C$ is any holomorphic function + $f:\Omega\mapsto \Omega'$ such that + $f'(z)\neq 0$ for all $z\in\Omega$. +\end{definition} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{demo}[that the definitions are equivalent] + We will denote in general $w=f(z)$. Consider, in the complex plane, two + line segments $\gamma_1$ and $\gamma_2$ contained inside the set $\Omega$ + where $f$ is defined, and intersecting at a point $z_0$ in $\Omega$. + Denote by $\gamma'_1$ and $\gamma_2'$ their images by~$f$. + + We want to show that if the angle between $\gamma_1$ and $\gamma_2$ is + equal to $\theta$, then the same holds for their images, which means that + the angle between the tangent lines to $\gamma'_1$ and $\gamma'_2$ at + $w_0=f(z_0)$ is also equal to $\theta$. + + Consider a point $z\in\gamma_1$ close to~$z_0$. Its image $w=f(z)$ + satisfies + \begin{equation*} + \lim_{z\to z_0} \frac{w-w_0}{z-z_0}=f'(z_0), + \end{equation*} + and hence + $$\displaystyle \lim_{z\to z_0} \Arg + (w-w_0)-\Arg(z-z_0) = \Arg f'(z_0), $$% + which shows that the angle between the curve $\gamma'_1$ and the real + axis is equal to the angle between the original segment $\gamma_1$ and + the real axis, plus the angle $\alpha=\Arg f'(z_0)$ (which is well + defined because $f'(z)\neq 0$). + + Similarly, the angle between the image curve $\gamma'_2$ and the real + axis is equal to that between the segment $\gamma_2$ and the real axis, + plus the same~$\alpha$. + + Therefore, the angle between the two image curves is the same as that + between the two line segments, namely, $\theta$. + + Another way to see this is as follows: the tangent vectors of the curves + are transformed according to the rule $\vect{V}'=\dd f_{z_0}\vect{V}$. But the + differential of $f$ (when $f$ is seen as a map from $\R^2$ to~$\R^2$) is + of the form + \begin{equation} + \displaystyle \dd f_{z_0}=\begin{pmatrix} + \displaystyle \dep{P}{x} & \displaystyle \dep{P}{y} \\[4mm] + \displaystyle \dep{Q}{x} & \displaystyle \dep{Q}{y}\end{pmatrix} + = + \abs{f'(z_0)}\begin{pmatrix}\cos\alpha& -\sin\alpha + \\ \sin\alpha &\cos\alpha \end{pmatrix}, + \label{eq:FSimil} + \end{equation} + where $\alpha$ is the argument of $f'(z_0)$. This is the matrix of a + rotation composed with a homothety, that is, a similitude. + + \medskip +%% ······································································ + % {\begin{picture}(300,100) + % \put(0,0){\epsfig{file=\Figures/TC.\Ext,height=3.2cm}} + % \put(20,65){$\gamma_2$} \put(80,55){$\theta$} + % \put(100,80){$\gamma_1$} \put(195,85){$\gamma'_1$} + % \put(245,35){$\theta$} \put(270,60){$\gamma'_2$} + % \end{picture}} +%% ······································································ + + Conversely, if $f$ is a map which is $\R^2$-differentiable and preserves + angles, then at any point $\dd f$ is an endomorphism of~$\R^2$ which + preserves angles. Since $f$ also preserves orientation, its determinant + is positive, so $\dd f$ is a similitude, and its matrix is exactly + as in equation~\eqref{eq:FSimil}. The Cauchy-Riemann equations are + immediate consequences. +\end{demo} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{remarque} + \index{Antiholomorphic function}% + \index{Function!antiholomorphic ---}% + An \emph{antiholomorphic} map also preserves angles, but it + reverses the orientation. +\end{remarque} +%% ---------------------------------------------------------------------- + +\newpage +\subsection*{Calcul différentiel} + + + +Pour obtenir la différentielle totale de cette expression, considérée comme fonction de $x$, $y$, ..., donnons à $x$, $y$, ... des accroissements $d\!x$, $d\!y$, .... Soient $\Delta u$, $\Delta v$, ..., $\Delta f$ les accroissements correspondants de $u$, $v$, ...,$f$. On aura +\begin{equation*} + \Delta f= \dfrac{\partial\! f}{\partial u} \Delta u + \dfrac{\partial\! f}{\partial v} \Delta v + \hdots + R\Delta u + R_1 \Delta v + \hdots, +\end{equation*} +$R$, $R_1$, ... tendant vers zéro avec $\Delta u$, $\Delta v$, .... + +Mais on a, d'autre part, +\begin{align*} + \Delta u & = \dfrac{\partial u}{\partial x} d\! x + + \dfrac{\partial u}{\partial y} \Delta y + \hdots + S\Delta x + S_1 \Delta y + \hdots \\ +& = du + Sd\! x + S_1 d\! y + \hdots \\ + \Delta v & = \dfrac{\partial v}{\partial x} d\! x + + \dfrac{\partial v}{\partial y} \Delta y + \hdots + T\Delta x + T_1 \Delta y + \hdots \\ +& = dv + Td\! x + T_1 d\! y + \hdots \\ +\hdots +\end{align*} +$S$, $S_1$, ..., $T$, $T_1$,... tendant vers zéro avec $d\! x$, $d\! y$, .... + +Substituant ces valeurs dans l'expression de $\Delta f$, il vient +\begin{equation*} +\begin{array}{rcl} + \vbox to 25pt {} \Delta f & = &\dfrac{\partial\! f}{\partial u} d u + \dfrac{\partial\! f}{\partial v} d v + \hdots + \rho d\! x + \rho_1 d\! y + \hdots \\ +\vbox to 25pt {}& = & \phantom{+} \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots \right) d\! x \\ +\vbox to 25pt {}& & + \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots \right) d\! y \\ +\vbox to 25pt {}&& + \hdots + \rho d\! x + \rho_1 d\! y + \hdots +\end{array} +\end{equation*} +$\rho$, $\rho_1$, ... tendant vers zéro avec $d\! x$, $d\! y$, .... + +On aura donc +\begin{align*} + \dfrac{\partial\! f}{\partial x}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots, \\ + \dfrac{\partial\! f}{\partial y}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots, \\ +\hdots +\end{align*} +et, d'autre part, +\begin{equation*} + df = \dfrac{\partial\! f}{\partial u} {\mathrm d} u + \dfrac{\partial\! f}{\partial v} {\mathrm d} v + \hdots ; +\end{equation*} +d'où les deux propositions suivantes : + +{\em La dérivée, par rapport à une variable indépendante $x$, d'une fonction composée $f(u,v,\hdots)$ s'obtient en ajoutant ensemble les dérivées partielles $\dfrac{\partial\! f}{\partial u}$, $\dfrac{\partial\! f}{\partial v}$, ..., respectivement multipliées par les dérivées de $u$, $v$, ... par rapport à $x$. + +La différentielle totale $df$ s'exprimer au moyen de $u$, $v$, ..., $du$, $dv$, ..., de la même manière que si $u$, $v$, ... étaient des variables indépendantes. +} + +\hbox to \textwidth { \hfill + {\sc Camille Jordan}, {\em Cours d'analyse de l'\'Ecole polytechnique} +} + +\end{document} diff --git a/Master/texmf-dist/doc/fonts/mathdesign/MD-urw-GaramondNo8-example.tex b/Master/texmf-dist/doc/fonts/mathdesign/MD-urw-GaramondNo8-example.tex new file mode 100644 index 00000000000..314fe134cb3 --- /dev/null +++ b/Master/texmf-dist/doc/fonts/mathdesign/MD-urw-GaramondNo8-example.tex @@ -0,0 +1,271 @@ +\documentclass[12pt]{article} + +\usepackage[T1]{fontenc} +\usepackage[latin1]{inputenc} +% \usepackage[french]{babel} +\usepackage{amsmath} +\usepackage{amsthm} +%\usepackage{mathrsfs} +\newtheorem{theorem}{Theorem}[section] +\newtheorem{definition}{Definition}[section] +\newenvironment{demo}{\noindent {\bf Dem.}}{\qed} +\newenvironment{remarque}{\noindent {\bf Rem.} \small \itshape}{} +\newenvironment{exemple}{\noindent {\bf Example}}{} + +\newcommand{\Lu}{L^1(\Rset)} +\newcommand{\tf}[1]{{\cal F}\left(#1\right)} +\newcommand{\ii}{{\mathrm{i}}} +\newcommand{\Cn}{{\cal C}^{n}} +\newcommand{\dd}{\mathrm{d}} +% ;; \newcommand{\Rset}{{\mathbb R}} +\newcommand{\Rset}{R} +\newcommand{\R}{\mathbb R} +\newcommand{\C}{\mathbb R} +\newcommand{\ex}{\mathrm{e}} +\newcommand{\Cinf}{{\cal C}^{\infty}} +\newcommand{\abs}[1]{\left| #1 \right|} +\newcommand{\dx}{\dd x} +\newcommand{\ds}{\displaystyle} +\newcommand{\vect}[1]{\overrightarrow{#1}} +\newcommand{\Boule}[2]{\mathscr B(#1,#2)} +\newcommand{\Cercle}[2]{\mathscr C(#1,#2)} +\DeclareMathOperator{\Arg}{Arg} + +\newcommand{\dep}[2]{\ds \frac{\partial #1}{\partial #2}} + +\title{Example of the \textsf{mdugm} fonts.} + +\author{Paul Pichaureau} + + +\usepackage[cal=scr,mdugm,greekfamily = didot]{mathdesign} +%% \usepackage{amssymb} + +\begin{document} + +\maketitle + +\begin{abstract} + The package \textsf{mdugm} consists of a full set of + mathematical fonts, designed to be combined with Urw + Garamondno8 as the main text font. + + This example is extracted from the excellent book {\em + Mathematics for Physics and Physicists}, {\sc W. Appel}, + Princeton University Press, {\sc 2007}. + +\end{abstract} + + +\section{Conformal maps} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +\subsection{Preliminaries} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +Consider a change of variable $(x,y)\mapsto +(u,v)=\big(u(x,y),v(x,y)\big)$ in the plane $\R^2$, identified +with~$\C$. This change of variable really only deserves the name if +$f$ is locally bijective (i.e., one-to-one); this is the case if the +jacobian of the map is nonzero (then so is the jacobian of the +inverse map): +\begin{equation*} + \left| \frac{{D}(u,v)}{{D}(x,y)}\right| = + \begin{vmatrix} + \ds\frac{\displaystyle\partial u}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial u}{\displaystyle\partial y} \\[4mm] + \ds\frac{\displaystyle\partial v}{\displaystyle\partial x} & + \ds\frac{\displaystyle\partial v}{\displaystyle\partial y} + \end{vmatrix}\neq 0 + \qquad\text{and}\qquad + \left| \frac{{D}(x,y)}{{D}(u,v)}\right| + =\begin{vmatrix}\ds\dep{x}{u} &\ds \dep{x}{v}\\[4mm] + \ds\dep{y}{u} &\ds \dep{y}{v} + \end{vmatrix}\neq 0. +\end{equation*} +\begin{theorem} +In a complex change of variable +\begin{equation*} + z= x+\ii y\longmapsto w=f(z)=u+\ii v, +\end{equation*} +and \emph{if $f$ is holomorphic}, then the jacobian of the map is equal to +\begin{equation*} + J_f(z)=\left| \frac{{D}(u,v)}{{D}(x,y)}\right|= + \abs{f'(z)}^2. +\end{equation*} +\end{theorem} +\begin{demo} + Indeed, we have $f'(z)=\dep{u}{x}+\ii\dep{v}{x}$ and hence, by the + Cauchy-Riemann relations, + \begin{align*} + \abs{f'(z)}^2 & = + \left(\dep{u}{x}\right)^2+\left(\dep{v}{x}\right)^2 + = + \dep{u}{x}\dep{v}{y}-\dep{v}{x}\dep{u}{y}=J_f(z). + \end{align*} +\end{demo} + +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal map} or \emph{conformal transformation} of an + open subset $\Omega\subset\R^2$ into another open subset + $\Omega'\subset\R^2$ is any map $f:\Omega\mapsto \Omega'$, locally + bijective, that preserves angles and orientation. +\end{definition} + +\begin{theorem} + Any conformal map is given by a holomorphic function $f$ such + that the derivative of $f$ does not vanish. +\end{theorem} + +This justifies the next definition: +%% ---------------------------------------------------------------------- +\begin{definition} + \index{Conformal map}% + \index{Transformation!conformal ---}% + A \emph{conformal transformation} or \emph{conformal map} of + an open subset + $\Omega\subset\C$ into another open subset + $\Omega'\subset\C$ is any holomorphic function + $f:\Omega\mapsto \Omega'$ such that + $f'(z)\neq 0$ for all $z\in\Omega$. +\end{definition} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{demo}[that the definitions are equivalent] + We will denote in general $w=f(z)$. Consider, in the complex plane, two + line segments $\gamma_1$ and $\gamma_2$ contained inside the set $\Omega$ + where $f$ is defined, and intersecting at a point $z_0$ in $\Omega$. + Denote by $\gamma'_1$ and $\gamma_2'$ their images by~$f$. + + We want to show that if the angle between $\gamma_1$ and $\gamma_2$ is + equal to $\theta$, then the same holds for their images, which means that + the angle between the tangent lines to $\gamma'_1$ and $\gamma'_2$ at + $w_0=f(z_0)$ is also equal to $\theta$. + + Consider a point $z\in\gamma_1$ close to~$z_0$. Its image $w=f(z)$ + satisfies + \begin{equation*} + \lim_{z\to z_0} \frac{w-w_0}{z-z_0}=f'(z_0), + \end{equation*} + and hence + $$\displaystyle \lim_{z\to z_0} \Arg + (w-w_0)-\Arg(z-z_0) = \Arg f'(z_0), $$% + which shows that the angle between the curve $\gamma'_1$ and the real + axis is equal to the angle between the original segment $\gamma_1$ and + the real axis, plus the angle $\alpha=\Arg f'(z_0)$ (which is well + defined because $f'(z)\neq 0$). + + Similarly, the angle between the image curve $\gamma'_2$ and the real + axis is equal to that between the segment $\gamma_2$ and the real axis, + plus the same~$\alpha$. + + Therefore, the angle between the two image curves is the same as that + between the two line segments, namely, $\theta$. + + Another way to see this is as follows: the tangent vectors of the curves + are transformed according to the rule $\vect{V}'=\dd f_{z_0}\vect{V}$. But the + differential of $f$ (when $f$ is seen as a map from $\R^2$ to~$\R^2$) is + of the form + \begin{equation} + \displaystyle \dd f_{z_0}=\begin{pmatrix} + \displaystyle \dep{P}{x} & \displaystyle \dep{P}{y} \\[4mm] + \displaystyle \dep{Q}{x} & \displaystyle \dep{Q}{y}\end{pmatrix} + = + \abs{f'(z_0)}\begin{pmatrix}\cos\alpha& -\sin\alpha + \\ \sin\alpha &\cos\alpha \end{pmatrix}, + \label{eq:FSimil} + \end{equation} + where $\alpha$ is the argument of $f'(z_0)$. This is the matrix of a + rotation composed with a homothety, that is, a similitude. + + \medskip +%% ······································································ + % {\begin{picture}(300,100) + % \put(0,0){\epsfig{file=\Figures/TC.\Ext,height=3.2cm}} + % \put(20,65){$\gamma_2$} \put(80,55){$\theta$} + % \put(100,80){$\gamma_1$} \put(195,85){$\gamma'_1$} + % \put(245,35){$\theta$} \put(270,60){$\gamma'_2$} + % \end{picture}} +%% ······································································ + + Conversely, if $f$ is a map which is $\R^2$-differentiable and preserves + angles, then at any point $\dd f$ is an endomorphism of~$\R^2$ which + preserves angles. Since $f$ also preserves orientation, its determinant + is positive, so $\dd f$ is a similitude, and its matrix is exactly + as in equation~\eqref{eq:FSimil}. The Cauchy-Riemann equations are + immediate consequences. +\end{demo} +%% ---------------------------------------------------------------------- + +%% ---------------------------------------------------------------------- +\begin{remarque} + \index{Antiholomorphic function}% + \index{Function!antiholomorphic ---}% + An \emph{antiholomorphic} map also preserves angles, but it + reverses the orientation. +\end{remarque} +%% ---------------------------------------------------------------------- + +\newpage +\subsection*{Calcul différentiel} + + + +Pour obtenir la différentielle totale de cette expression, considérée comme fonction de $x$, $y$, ..., donnons à $x$, $y$, ... des accroissements $d\!x$, $d\!y$, .... Soient $\Delta u$, $\Delta v$, ..., $\Delta f$ les accroissements correspondants de $u$, $v$, ...,$f$. On aura +\begin{equation*} + \Delta f= \dfrac{\partial\! f}{\partial u} \Delta u + \dfrac{\partial\! f}{\partial v} \Delta v + \hdots + R\Delta u + R_1 \Delta v + \hdots, +\end{equation*} +$R$, $R_1$, ... tendant vers zéro avec $\Delta u$, $\Delta v$, .... + +Mais on a, d'autre part, +\begin{align*} + \Delta u & = \dfrac{\partial u}{\partial x} d\! x + + \dfrac{\partial u}{\partial y} \Delta y + \hdots + S\Delta x + S_1 \Delta y + \hdots \\ +& = du + Sd\! x + S_1 d\! y + \hdots \\ + \Delta v & = \dfrac{\partial v}{\partial x} d\! x + + \dfrac{\partial v}{\partial y} \Delta y + \hdots + T\Delta x + T_1 \Delta y + \hdots \\ +& = dv + Td\! x + T_1 d\! y + \hdots \\ +\hdots +\end{align*} +$S$, $S_1$, ..., $T$, $T_1$,... tendant vers zéro avec $d\! x$, $d\! y$, .... + +Substituant ces valeurs dans l'expression de $\Delta f$, il vient +\begin{equation*} +\begin{array}{rcl} + \vbox to 25pt {} \Delta f & = &\dfrac{\partial\! f}{\partial u} d u + \dfrac{\partial\! f}{\partial v} d v + \hdots + \rho d\! x + \rho_1 d\! y + \hdots \\ +\vbox to 25pt {}& = & \phantom{+} \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots \right) d\! x \\ +\vbox to 25pt {}& & + \left( \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots \right) d\! y \\ +\vbox to 25pt {}&& + \hdots + \rho d\! x + \rho_1 d\! y + \hdots +\end{array} +\end{equation*} +$\rho$, $\rho_1$, ... tendant vers zéro avec $d\! x$, $d\! y$, .... + +On aura donc +\begin{align*} + \dfrac{\partial\! f}{\partial x}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial x} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial x} + \hdots, \\ + \dfrac{\partial\! f}{\partial y}& = \dfrac{\partial\! f}{\partial u} \dfrac{\partial u}{\partial y} + \dfrac{\partial\! f}{\partial v} \dfrac{\partial v}{\partial y} + \hdots, \\ +\hdots +\end{align*} +et, d'autre part, +\begin{equation*} + df = \dfrac{\partial\! f}{\partial u} {\mathrm d} u + \dfrac{\partial\! f}{\partial v} {\mathrm d} v + \hdots ; +\end{equation*} +d'où les deux propositions suivantes : + +{\em La dérivée, par rapport à une variable indépendante $x$, d'une fonction composée $f(u,v,\hdots)$ s'obtient en ajoutant ensemble les dérivées partielles $\dfrac{\partial\! f}{\partial u}$, $\dfrac{\partial\! f}{\partial v}$, ..., respectivement multipliées par les dérivées de $u$, $v$, ... par rapport à $x$. + +La différentielle totale $df$ s'exprimer au moyen de $u$, $v$, ..., $du$, $dv$, ..., de la même manière que si $u$, $v$, ... étaient des variables indépendantes. +} + +\hbox to \textwidth { \hfill + {\sc Camille Jordan}, {\em Cours d'analyse de l'\'Ecole polytechnique} +} + +\end{document} |