Tutorial: Move step 10 to step 4

Shifts steps 4-9 to 5-10.

2 files changed, 36 insertions, 29 deletions

diff --git a/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
index 9ede4b3..a832003 100644
--- a/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
+++ b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt
@@ -1,29 +1,37 @@
-# first we add the executable that generates the table
-add_executable(MakeTable MakeTable.cxx)
-
-# add the command to generate the source code
-add_custom_command(
-  OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-  COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-  DEPENDS MakeTable
-  )
-
-# add the main library
-add_library(MathFunctions
-            mysqrt.cxx
-            ${CMAKE_CURRENT_BINARY_DIR}/Table.h
-            )
+add_library(MathFunctions mysqrt.cxx)
 
 # state that anybody linking to us needs to include the current source dir
 # to find MathFunctions.h, while we don't.
-# state that we depend on Tutorial_BINARY_DIR but consumers don't, as the
-# TutorialConfig.h include is an implementation detail
-# state that we depend on our binary dir to find Table.h
 target_include_directories(MathFunctions
           INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
-          PRIVATE ${CMAKE_CURRENT_BINARY_DIR}
           )
 
+target_link_libraries(MathFunctions tutorial_compiler_flags)
+
+# does this system provide the log and exp functions?
+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)
+  target_compile_definitions(MathFunctions
+                             PRIVATE "HAVE_LOG" "HAVE_EXP")
+endif()
+
 # install rules
-install(TARGETS MathFunctions DESTINATION lib)
+set(installable_libs MathFunctions tutorial_compiler_flags)
+install(TARGETS ${installable_libs} 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 7d80ee9..7eecd26 100644
--- a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
+++ b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
@@ -1,10 +1,8 @@
+#include <cmath>
 #include <iostream>
 
 #include "MathFunctions.h"
 
-// include the generated table
-#include "Table.h"
-
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -12,12 +10,13 @@ double mysqrt(double x)
     return 0;
   }
 
-  // use the table to help find an initial value
+  // if we have both log and exp then use them
+#if defined(HAVE_LOG) && defined(HAVE_EXP)
+  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
   double result = x;
-  if (x >= 1 && x < 10) {
-    std::cout << "Use the table to help find an initial value " << std::endl;
-    result = sqrtTable[static_cast<int>(x)];
-  }
 
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
@@ -28,6 +27,6 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-
+#endif
   return result;
 }