Ex8 and minor improvements

sheet3/8/userset.cpp

@@ -0,0 +1,16 @@
+#include "userset.h"
+#include <cmath>
+
+
+double FunctF(double const x, double const y)
+{
+// return  std::sin(3.14159*1*x)*std::sin(3.14159*1*y);
+//  return 16.0*1024. ;
+// return (double)1.0 ;
+    return x * x * std::sin(2.5 * 3.14159 * y);
+}
+
+double FunctU(const double /* x */, double const /* y */)
+{
+    return 1.0 ;
+}