mjo-complex.tex: new file with a \compconj (complex conjugate) command.

[mjotex.git] / examples.tex

diff --git a/examples.tex b/examples.tex
index ee0409699b5a5041fe833e90dac720b8223d04f1..a202da7bf69cc28ba3cda55b448f0edf11d6edf7 100644 (file)
--- a/examples.tex
+++ b/examples.tex
@@ -28,20 +28,29 @@
   \begin{section}{Arrow}
     The identity operator on $V$ is $\identity{V}$. The composition of
     $f$ and $g$ is $\compose{f}{g}$. The inverse of $f$ is
-    $\inverse{f}$.
+    $\inverse{f}$. If $f$ is a function and $A$ is a subset of its
+    domain, then the preimage under $f$ of $A$ is $\preimage{f}{A}$.
   \end{section}
 
   \begin{section}{Common}
     The function $f$ applied to $x$ is $f\of{x}$. We can group terms
     like $a + \qty{b - c}$ or $a + \qty{b - \sqty{c - d}}$. Here's a
     set $\set{1,2,3} = \setc{n \in \Nn[1]}{ n \le 3 }$. Here's a pair
-    of things $\pair{1}{2}$ or a triple of them
-    $\triple{1}{2}{3}$. The Cartesian product of two sets $A$ and $B$
-    is $\cartprod{A}{B}$; if we take the product with $C$ as well,
-    then we obtain $\cartprodthree{A}{B}{C}$. The direct sum of $V$
-    and $W$ is $\directsum{V}{W}$ and the factorial of the number $10$
-    is $\factorial{10}$.
-
+    of things $\pair{1}{2}$ or a triple of them $\triple{1}{2}{3}$,
+    and the factorial of the number $10$ is $\factorial{10}$.
+
+    The Cartesian product of two sets $A$ and $B$ is
+    $\cartprod{A}{B}$; if we take the product with $C$ as well, then
+    we obtain $\cartprodthree{A}{B}{C}$. The direct sum of $V$ and $W$
+    is $\directsum{V}{W}$. Or three things,
+    $\directsumthree{U}{V}{W}$. How about more things? Like
+    $\directsummany{k=1}{\infty}{V_{k}} \ne
+    \cartprodmany{k=1}{\infty}{V_{k}}$. Those direct sums and
+    cartesian products adapt nicely to display equations:
+    %
+    \begin{equation*}
+      \directsummany{k=1}{\infty}{V_{k}} \ne \cartprodmany{k=1}{\infty}{V_{k}}.
+    \end{equation*}
     Here are a few common tuple spaces that should not have a
     superscript when that superscript would be one: $\Nn[1]$,
     $\Zn[1]$, $\Qn[1]$, $\Rn[1]$, $\Cn[1]$. However, if the
@@ -55,12 +64,25 @@
     (indexed) union and intersections of things, like
     $\unionmany{k=1}{\infty}{A_{k}}$ or
     $\intersectmany{k=1}{\infty}{B_{k}}$. The best part about those
-    are that they do the right thing in a display equation:
+    is that they do the right thing in a display equation:
     %
     \begin{equation*}
       \unionmany{k=1}{\infty}{A_{k}} = \intersectmany{k=1}{\infty}{B_{k}}
     \end{equation*}
+
+    Finally, we have the four standard types of intervals in $\Rn[1]$,
     %
+    \begin{align*}
+      \intervaloo{a}{b} &= \setc{ x \in \Rn[1]}{ a < x < b },\\
+      \intervaloc{a}{b} &= \setc{ x \in \Rn[1]}{ a < x \le b },\\
+      \intervalco{a}{b} &= \setc{ x \in \Rn[1]}{ a \le x < b }, \text{ and }\\
+      \intervalcc{a}{b} &= \setc{ x \in \Rn[1]}{ a \le x \le b }.
+    \end{align*}
+  \end{section}
+
+  \begin{section}{Complex}
+    We sometimes want to conjugate complex numbers like
+    $\compconj{a+bi} = a - bi$.
   \end{section}
 
   \begin{section}{Cone}
@@ -90,7 +112,9 @@
     their tensor product is $\tp{x}{y}$. The Kronecker product of
     matrices $A$ and $B$ is $\kp{A}{B}$. The adjoint of the operator
     $L$ is $\adjoint{L}$, or if it's a matrix, then its transpose is
-    $\transpose{L}$. Its trace is $\trace{L}$.
+    $\transpose{L}$. Its trace is $\trace{L}$. Another matrix-specific
+    concept is the Moore-Penrose pseudoinverse of $L$, denoted by
+    $\pseudoinverse{L}$.
 
     The span of a set $X$ is $\spanof{X}$, and its codimension is
     $\codim{X}$. The projection of $X$ onto $V$ is $\proj{V}{X}$. The
@@ -103,6 +127,30 @@
     The set of all bounded linear operators from $V$ to $W$ is
     $\boundedops[W]{V}$. If $W = V$, then we write $\boundedops{V}$
     instead.
+
+    The direct sum of $V$ and $W$ is $\directsum{V}{W}$, of course,
+    but what if $W = V^{\perp}$? Then we wish to indicate that fact by
+    writing $\directsumperp{V}{W}$. That operator should survive a
+    display equation, too, and the weight of the circle should match
+    that of the usual direct sum operator.
+    %
+    \begin{align*}
+      Z = \directsumperp{V}{W}\\
+      \oplus \oplusperp \oplus \oplusperp
+    \end{align*}
+    %
+    Its form should also survive in different font sizes...
+    \Large
+    \begin{align*}
+      Z = \directsumperp{V}{W}\\
+      \oplus \oplusperp \oplus \oplusperp
+    \end{align*}
+    \Huge
+    \begin{align*}
+      Z = \directsumperp{V}{W}\\
+      \oplus \oplusperp \oplus \oplusperp
+    \end{align*}
+    \normalsize
   \end{section}
 
   \begin{section}{Listing}
@@ -236,5 +284,5 @@
     The interior of a set $X$ is $\interior{X}$. Its closure is
     $\closure{X}$ and its boundary is $\boundary{X}$.
   \end{section}
-  
+
 \end{document}