superscript when that superscript would be one: $\Nn[1]$,
$\Zn[1]$, $\Qn[1]$, $\Rn[1]$, $\Cn[1]$. However, if the
superscript is (say) two, then it appears: $\Nn[2]$, $\Zn[2]$,
- $\Qn[2]$, $\Rn[2]$, $\Cn[2]$. Likewise we have the $n$-by-$n$
- real-symmetric and complex-Hermitian matrices $\Sn$ and $\Hn$
- respectively; however $\Sn[1]$ and $\Hn[1]$ do not automatically
- simplify because the ``$n$'' does not indicate the arity of a
- Cartesian product in this case.
+ $\Qn[2]$, $\Rn[2]$, $\Cn[2]$.
We also have a few basic set operations, for example the union of
two or three sets: $\union{A}{B}$, $\unionthree{A}{B}{C}$. And of
$\transpose{L}$. Its trace is $\trace{L}$. Another matrix-specific
concept is the Moore-Penrose pseudoinverse of $L$, denoted by
$\pseudoinverse{L}$. Finally, the rank of a matrix $L$ is
- $\rank{L}$.
+ $\rank{L}$. As far as matrix spaces go, we have the $n$-by-$n$
+ real-symmetric and complex-Hermitian matrices $\Sn$ and $\Hn$
+ respectively; however $\Sn[1]$ and $\Hn[1]$ do not automatically
+ simplify because the ``$n$'' does not indicate the arity of a
+ Cartesian product in this case.
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
\fi
-% The space of real symmetric n-by-n matrices. Does not reduce to
-% merely "S" when n=1 since S^{n} does not mean an n-fold cartesian
-% product of S^{1}.
-\newcommand*{\Sn}[1][n]{ \mathcal{S}^{#1} }
-\ifdefined\newglossaryentry
- \newglossaryentry{Sn}{
- name={\ensuremath{\Sn}},
- description={the set of $n$-by-$n$ real symmetric matrices},
- sort=Sn
- }
-\fi
-
-% The space of complex Hermitian n-by-n matrices. Does not reduce to
-% merely "H" when n=1 since H^{n} does not mean an n-fold cartesian
-% product of H^{1}.
-\newcommand*{\Hn}[1][n]{ \mathcal{H}^{#1} }
-\ifdefined\newglossaryentry
- \newglossaryentry{Hn}{
- name={\ensuremath{\Hn}},
- description={the set of $n$-by-$n$ complex Hermitian matrices},
- sort=Hn
- }
-\fi
-
-
%
% Basic set operations
%
\newcommand*{\directsumperp}[2]{ {#1}\oplusperp{#2} }
+% The space of real symmetric n-by-n matrices. Does not reduce to
+% merely "S" when n=1 since S^{n} does not mean an n-fold cartesian
+% product of S^{1}.
+\newcommand*{\Sn}[1][n]{ \mathcal{S}^{#1} }
+\ifdefined\newglossaryentry
+ \newglossaryentry{Sn}{
+ name={\ensuremath{\Sn}},
+ description={the set of $n$-by-$n$ real symmetric matrices},
+ sort=Sn
+ }
+\fi
+
+% The space of complex Hermitian n-by-n matrices. Does not reduce to
+% merely "H" when n=1 since H^{n} does not mean an n-fold cartesian
+% product of H^{1}.
+\newcommand*{\Hn}[1][n]{ \mathcal{H}^{#1} }
+\ifdefined\newglossaryentry
+ \newglossaryentry{Hn}{
+ name={\ensuremath{\Hn}},
+ description={the set of $n$-by-$n$ complex Hermitian matrices},
+ sort=Hn
+ }
+\fi
+
+
\fi