From 1141b2e9b4fc90b5ce77a779d2154760e62d7643 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20L=C3=B6fberg?= <johanl@isy.liu.se>
Date: Fri, 28 Jun 2024 10:51:42 +0200
Subject: [PATCH] Fixes #1418 entropy detection failed

---
 @sdpvar/mtimes.m | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/@sdpvar/mtimes.m b/@sdpvar/mtimes.m
index f477410a..b374c44b 100644
--- a/@sdpvar/mtimes.m
+++ b/@sdpvar/mtimes.m
@@ -817,15 +817,21 @@
 args = args.arg{1};
 % Temporarily recast slog as log (slog is log(1+x))
 if isequal(Y.extra.opname,'slog')
-    args = args + 1;
-    Y.extra.opname = 'log';
+    if nnz(getbasematrix(X,0))==0
+        % Not entropy but fits cross entropy
+        Z = -crossentropy(X,args + 1);
+    else
+        % Still hope for entropy
+        args = args + 1;
+        Y.extra.opname = 'log';
+    end     
 end
 % Detect the case log(f)*(k*f), and rescale to k*log(f)*f
 % to simplify comparison of function argument and outer argument
 if isequal(X.dim,args.dim) && isequal(size(X.basis),size(args.basis))
     [~,~,a] = find(X.basis);
     [~,~,b] = find(args.basis);
-    if ~isequal(a,b)
+    if ~isequal(a,b) && all(size(a) == size(b))
         c = a./b;
         if all(abs(c-c(1))<=1e-13)           
             k = c(1);