Tutorial: Improve Step 5

* Updated output message
* Use 'target_compile_definitions' for HAVE_LOG and HAVE_EXP

Previously, the change from using TutorialConfig.h to
target_compile_definitions happened without explanation as part of Step 8.

Help/guide/tutorial/Step11/MathFunctions/CMakeLists.txt

@@ -11,12 +11,6 @@ target_include_directories(MathFunctions
 option(USE_MYMATH "Use tutorial provided math implementation" ON)
 if(USE_MYMATH)
 
-  # does this system provide the log and exp functions?
-  include(CheckSymbolExists)
-  set(CMAKE_REQUIRED_LIBRARIES "m")
-  check_symbol_exists(log "math.h" HAVE_LOG)
-  check_symbol_exists(exp "math.h" HAVE_EXP)
-
   # first we add the executable that generates the table
   add_executable(MakeTable MakeTable.cxx)
   target_link_libraries(MakeTable tutorial_compiler_flags)

Help/guide/tutorial/Step11/MathFunctions/mysqrt.cxx

@@ -18,8 +18,8 @@ double mysqrt(double x)
   // if we have both log and exp then use them
 #if defined(HAVE_LOG) && defined(HAVE_EXP)
   double result = exp(log(x) * 0.5);
-  std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
-            << std::endl;
+  std::cout << "Computing sqrt of " << x << " to be " << result
+            << " using log and exp" << std::endl;
 #else
   // use the table to help find an initial value
   double result = x;
@@ -38,7 +38,7 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-#endif
+
   return result;
 }
 }