Tutorial: Update step 7 style

Help/guide/tutorial/Step7/MathFunctions/CMakeLists.txt

@@ -9,6 +9,26 @@ target_include_directories(MathFunctions
 # 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)

Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx

@@ -1,5 +1,6 @@
 #include <iostream>
 
+// TODO 4: include cmath
 #include "MathFunctions.h"
 
 // a hack square root calculation using simple operations
@@ -9,6 +10,14 @@ double mysqrt(double x)
     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
@@ -20,5 +29,6 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
+
   return result;
 }