Tutorial: Improve Step 6

* Print message when using the table
* Remove duplicated comment
* Remove HAVE_LOG and HAVE_EXP checks, use generated table instead

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

@@ -13,12 +13,6 @@ 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)
 
@@ -44,10 +38,6 @@ if(USE_MYMATH)
                         POSITION_INDEPENDENT_CODE ${BUILD_SHARED_LIBS}
                         )
 
-  target_compile_definitions(SqrtLibrary PRIVATE
-                             "$<$<BOOL:${HAVE_LOG}>:HAVE_LOG>"
-                             "$<$<BOOL:${HAVE_EXP}>:HAVE_EXP>"
-                             )
   target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
 endif()
 

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

@@ -4,8 +4,6 @@
 // include the generated table
 #include "Table.h"
 
-#include <cmath>
-
 namespace mathfunctions {
 namespace detail {
 // a hack square root calculation using simple operations
@@ -15,12 +13,6 @@ double mysqrt(double x)
     return 0;
   }
 
-  // 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 and exp" << std::endl;
-#else
   // use the table to help find an initial value
   double result = x;
   if (x >= 1 && x < 10) {
@@ -38,7 +30,7 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-#endif
+
   return result;
 }
 }