3 files changed, 71 insertions, 0 deletions
diff --git a/Help/guide/tutorial/Step7/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step7/MathFunctions/CMakeLists.txt
new file mode 100644
index 0000000..e5bdc4d
--- /dev/null
+++ b/Help/guide/tutorial/Step7/MathFunctions/CMakeLists.txt
@@ -0,0 +1,36 @@
+add_library(MathFunctions mysqrt.cxx)
+
+# state that anybody linking to us needs to include the current source dir
+# to find MathFunctions.h, while we don't.
+target_include_directories(MathFunctions
+          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+          )
+
+# link our compiler flags interface library
+target_link_libraries(MathFunctions tutorial_compiler_flags)
+
+# TODO 1: Include CheckCXXSourceCompiles
+
+# TODO 2: Use check_cxx_source_compiles with simple C++ code to verify
+# availability of:
+# * std::log
+# * std::exp
+# Store the results in HAVE_LOG and HAVE_EXP respectively.
+
+# Hint: Sample C++ code which uses log:
+# #include <cmath>
+# int main() {
+#   std::log(1.0);
+#   return 0;
+# }
+
+# TODO 3: Conditionally on HAVE_LOG and HAVE_EXP, add private compile
+# definitions "HAVE_LOG" and "HAVE_EXP" to the MathFunctions target.
+
+#Hint: Use target_compile_definitions()
+
+# install libs
+set(installable_libs MathFunctions tutorial_compiler_flags)
+install(TARGETS ${installable_libs} DESTINATION lib)
+# install include headers
+install(FILES MathFunctions.h DESTINATION include)
diff --git a/Help/guide/tutorial/Step7/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step7/MathFunctions/MathFunctions.h
new file mode 100644
index 0000000..cd36bcc
--- /dev/null
+++ b/Help/guide/tutorial/Step7/MathFunctions/MathFunctions.h
@@ -0,0 +1 @@
+double mysqrt(double x);
diff --git a/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx
new file mode 100644
index 0000000..3d2492a
--- /dev/null
+++ b/Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx
@@ -0,0 +1,34 @@
+#include <iostream>
+
+// TODO 4: include cmath
+#include "MathFunctions.h"
+
+// a hack square root calculation using simple operations
+double mysqrt(double x)
+{
+  if (x <= 0) {
+    return 0;
+  }
+
+  // TODO 5: If both HAVE_LOG and HAVE_EXP are defined,  use the following:
+  //// double result = std::exp(std::log(x) * 0.5);
+  //// std::cout << "Computing sqrt of " << x << " to be " << result
+  ////        << " using log and exp" << std::endl;
+  // else, use the existing logic.
+
+  // Hint: Don't forget the #endif before returning the result!
+
+  double result = x;
+
+  // do ten iterations
+  for (int i = 0; i < 10; ++i) {
+    if (result <= 0) {
+      result = 0.1;
+    }
+    double delta = x - (result * result);
+    result = result + 0.5 * delta / result;
+    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
+  }
+
+  return result;
+}