From 24fbc0d923e5f8db8f5ea0dd895368970e252742 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Adjemian=20=28Argos=29?=
 <stepan@adjemian.eu>
Date: Mon, 12 Feb 2024 17:48:11 +0100
Subject: [PATCH] Create a sparse identifty matrix when it makes sense.

---
 matlab/optimization/solve1.m | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/matlab/optimization/solve1.m b/matlab/optimization/solve1.m
index 5c2cd1246..fa2cac7c2 100644
--- a/matlab/optimization/solve1.m
+++ b/matlab/optimization/solve1.m
@@ -123,7 +123,11 @@ for its = 1:maxit
         fjac2=fjac'*fjac;
         temp=max(sum(abs(fjac2)));
         if temp>0
-            p=-(fjac2+sqrt(nn*eps)*temp*eye(nn))\(fjac'*fvec);
+            if issparse(fjac)
+                p=-(fjac2+sqrt(nn*eps)*temp*speye(nn))\(fjac'*fvec);
+            else
+                p=-(fjac2+sqrt(nn*eps)*temp*eye(nn))\(fjac'*fvec);
+            end
         else
             errorflag = true;
             errorcode = 5;