1 files changed, 19 insertions, 0 deletions
diff --git a/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx
new file mode 100644
index 0000000000..dc28b4b530
--- /dev/null
+++ b/Help/guide/tutorial/Step3/MathFunctions/MathFunctions.cxx
@@ -0,0 +1,19 @@
+#include "MathFunctions.h"
+
+#include <cmath>
+
+#ifdef USE_MYMATH
+#  include "mysqrt.h"
+#endif
+
+namespace mathfunctions {
+double sqrt(double x)
+{
+// which square root function should we use?
+#ifdef USE_MYMATH
+  return detail::mysqrt(x);
+#else
+  return std::sqrt(x);
+#endif
+}
+}