X-Git-Url: http://gitweb.michael.orlitzky.com/?p=mjotex.git;a=blobdiff_plain;f=mjo-cone.tex;fp=mjo-cone.tex;h=c556f4b14338306b8537a931f7f91c7588e5e310;hp=a7507d60778bf4a01b560cb1b41c97e36a77ff9b;hb=9e823aa3dcf40f8bfd113476da576fb6b4c0180f;hpb=d8b66e409213fa4d3392f654081eb8dd85f03c4c

diff --git a/mjo-cone.tex b/mjo-cone.tex
index a7507d6..c556f4b 100644
--- a/mjo-cone.tex
+++ b/mjo-cone.tex
@@ -9,6 +9,10 @@
 
 \input{mjo-common}
 
+% The dual of a subset of an inner-product space; always a closed
+% convex cone.
+\newcommand*{\dual}[1]{ {#1}^{*} }
+
 %
 % Common cones.
 %
@@ -27,9 +31,25 @@
 
 
 %
-% Some collections of linear operators
+% Some collections of linear operators.
 %
 
+% The set of all positive operators on its argument. This uses the
+% same magic as \boundedops to accept either one or two arguments. If
+% one argument is given, the domain and codomain are equal and the
+% positive operators fix a subset of that space. When two arguments
+% are given, the positive operators send the first argument to a
+% subset of the second.
+\newcommand*{\posops}[2][]{
+  \pi\of{ {#2}
+    \if\relax\detokenize{#1}\relax
+      {}%
+    \else
+      {,{#1}}%
+    \fi
+  }
+}
+
 % The set of all S-operators on its argument.
 \newcommand*{\Sof}[1]{ \mathbf{S} \of{ {#1} } }