Merge topic 'tutorial-cmath' into release-3.23

5c84eca210 Tutorial: Simplify logic checking for cmath functions

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !7314

2 files changed, 16 insertions, 14 deletions

diff --git a/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
index f64c6ac..42e098a 100644
--- a/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
+++ b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
@@ -7,19 +7,21 @@ target_include_directories(MathFunctions
           )
 
 # does this system provide the log and exp functions?
-include(CheckSymbolExists)
-check_symbol_exists(log "math.h" HAVE_LOG)
-check_symbol_exists(exp "math.h" HAVE_EXP)
-if(NOT (HAVE_LOG AND HAVE_EXP))
-  unset(HAVE_LOG CACHE)
-  unset(HAVE_EXP CACHE)
-  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_link_libraries(MathFunctions PRIVATE m)
-  endif()
-endif()
+include(CheckCXXSourceCompiles)
+check_cxx_source_compiles("
+  #include <cmath>
+  int main() {
+    std::log(1.0);
+    return 0;
+  }
+" HAVE_LOG)
+check_cxx_source_compiles("
+  #include <cmath>
+  int main() {
+    std::exp(1.0);
+    return 0;
+  }
+" HAVE_EXP)
 
 # add compile definitions
 if(HAVE_LOG AND HAVE_EXP)
diff --git a/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
index 0637063..7eecd26 100644
--- a/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
+++ b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
@@ -12,7 +12,7 @@ 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);
+  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