helper: consider matrices with the same NANs and INFINITYs equal

to simplify bulk checks when these values are expected

matrix/helper_functions.hpp

@@ -23,8 +23,8 @@ bool is_finite(Type x) {
 /**
  * Compare if two floating point numbers are equal
  *
- * Note: Smaller or EQUAL than is important to correctly
- * handle the comparison to infinite or nan.
+ * NAN is considered equal to NAN and -NAN
+ * INFINITY is considered equal INFINITY but not -INFINITY
  *
  * @param x right side of equality check
  * @param y left side of equality check
@@ -36,7 +36,7 @@ bool isEqualF(const Type x, const Type y, const Type eps = 1e-4f)
 {
     return (matrix::fabs(x - y) <= eps)
            || (isnan(x) && isnan(y))
-           || (isinf(x) && isinf(y));
+           || (isinf(x) && isinf(y) && isnan(x - y));
 }
 
 /**