--- a/matlib/mat.hh	2003-01-06 23:47:26.000000000 +0100
+++ b/matlib/mat.copy.hh	2021-01-06 10:05:34.332415179 +0100
@@ -91,7 +91,7 @@
                 memcpy(c, r, d1 * d3 * sizeof(c[0]));
 }

-template<typename T> void mdet(const T *c, unsigned int d)
+template<typename T> int mdet(const T *c, unsigned int d)
 {
         T *c2;
         unsigned int i, j, k, l;