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.

2 files changed, 14 insertions, 5 deletions

diff --git a/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
index 3c3a816..8cc3ae3 100644
--- a/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
+++ b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
@@ -21,10 +21,20 @@ add_library(MathFunctions
 # state that we depend on our binary dir to find Table.h
 target_include_directories(MathFunctions
           INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
-          PRIVATE ${Tutorial_BINARY_DIR}
-                  ${CMAKE_CURRENT_BINARY_DIR}
+          PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
           )
 
+# 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)
+
+if(HAVE_LOG AND HAVE_EXP)
+  target_compile_definitions(MathFunctions
+                             PRIVATE "HAVE_LOG" "HAVE_EXP")
+endif()
+
 # install rules
 install(TARGETS MathFunctions DESTINATION lib)
 install(FILES MathFunctions.h DESTINATION include)
diff --git a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
index 5b862fb..2b1d889 100644
--- a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
+++ b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
@@ -1,5 +1,4 @@
 #include "MathFunctions.h"
-#include "TutorialConfig.h"
 #include <iostream>
 
 // include the generated table
@@ -17,8 +16,8 @@ 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;