delta_max and fix cabs2

src/complex_tools.c

@@ -0,0 +1,22 @@
+/*
+Copyright 2017-2023 Ian Jauslin
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include "complex_tools.h"
+
+// magnitude squared
+double cabs2(_Complex double x){
+  return (__real__ x)*(__real__ x)+(__imag__ x)*(__imag__ x);
+}