mjo-linear_algebra: add the \rank{} of a matrix (or EJA, or...).

diff --git a/examples.tex b/examples.tex
index c00279b16beb44514ae8e80e371d8dc3f8392a35..dde74d0f6997418a8ab283ee1f6fb53452f6a6bf 100644 (file)
--- a/examples.tex
+++ b/examples.tex
@@ -182,7 +182,8 @@
     $L$ is $\adjoint{L}$, or if it's a matrix, then its transpose is
     $\transpose{L}$. Its trace is $\trace{L}$. Another matrix-specific
     concept is the Moore-Penrose pseudoinverse of $L$, denoted by
-    $\pseudoinverse{L}$.
+    $\pseudoinverse{L}$. Finally, the rank of a matrix $L$ is
+    $\rank{L}$.
 
     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

diff --git a/mjo-linear_algebra.tex b/mjo-linear_algebra.tex
index e2ae9fa5b18c008639db087142911ba51a6c10b0..204ad05bd6b7981d32e2c56a4b268642d58d4ce2 100644 (file)
--- a/mjo-linear_algebra.tex
+++ b/mjo-linear_algebra.tex
@@ -51,6 +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}} }