X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo-linear_algebra.tex;h=204ad05bd6b7981d32e2c56a4b268642d58d4ce2;hb=66f91bd13a303f46822639420a20b5bffbe7a963;hp=5c3f715744b14db7b4984b063952f02ba5ac530e;hpb=7550b6a2e37298217b5cd4890299a64fb5cf1762;p=mjotex.git

diff --git a/mjo-linear_algebra.tex b/mjo-linear_algebra.tex
index 5c3f715..204ad05 100644
--- a/mjo-linear_algebra.tex
+++ b/mjo-linear_algebra.tex
@@ -1,15 +1,22 @@
 %
 % Standard operations from linear algebra.
 %
+\ifx\havemjolinearalgebra\undefined
+\def\havemjolinearalgebra{1}
 
-% Needed for \lvert, \rVert, etc. and \operatorname.
-\usepackage{amsmath}
 
-% Wasysym contains the \ocircle that we use in \directsumperp.
-\usepackage{wasysym}
+\ifx\lvert\undefined
+  \usepackage{amsmath} % \lvert, \rVert, etc. and \operatorname.
+\fi
 
-% Part of the adjustbox package; needed to clip the \perp sign.
-\usepackage{trimclip}
+\ifx\ocircle\undefined
+  \usepackage{wasysym}
+\fi
+
+\ifx\clipbox\undefined
+  % Part of the adjustbox package; needed to clip the \perp sign.
+  \usepackage{trimclip}
+\fi
 
 \input{mjo-common}
 
@@ -44,6 +51,17 @@
 % The trace of an operator.
 \newcommand*{\trace}[1]{ \operatorname{trace}\of{{#1}} }
 
+
+% The "rank" of its argument, which is context-dependent. It can mean
+% any or all of,
+%
+%   * the rank of a matrix,
+%   * the rank of a power-associative algebra (particularly an EJA),
+%   * the rank of an element in a Euclidean Jordan algebra.
+%
+\newcommand*{\rank}[1]{ \operatorname{rank}\of{{#1}} }
+
+
 % The ``span of'' operator. The name \span is already taken.
 \newcommand*{\spanof}[1]{ \operatorname{span}\of{{#1}} }
 
@@ -99,3 +117,6 @@
 
 % Now declare an orthogonal direct sum in terms of \oplusperp.
 \newcommand*{\directsumperp}[2]{ {#1}\oplusperp{#2} }
+
+
+\fi