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/Complete/MathFunctions/CMakeLists.txt

@@ -43,10 +43,6 @@ if(USE_MYMATH)
 
 
   target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
-  if(HAVE_LOG AND HAVE_EXP)
-    target_compile_definitions(SqrtLibrary
-                               PRIVATE "HAVE_LOG" "HAVE_EXP")
-  endif()
   target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
 endif()
 

Help/guide/tutorial/Complete/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
@@ -15,20 +13,13 @@ 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) {
+    std::cout << "Use the table to help find an initial value " << std::endl;
     result = sqrtTable[static_cast<int>(x)];
   }
 
-  // if we have both log and exp then use them
-
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
     if (result <= 0) {
@@ -38,7 +29,7 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-#endif
+
   return result;
 }
 }

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;
 }
 }

Help/guide/tutorial/Step10/MathFunctions/CMakeLists.txt

@@ -39,17 +39,6 @@ if(USE_MYMATH)
 
   target_compile_definitions(MathFunctions PRIVATE "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)
-
-  if(HAVE_LOG AND HAVE_EXP)
-    target_compile_definitions(SqrtLibrary
-                               PRIVATE "HAVE_LOG" "HAVE_EXP")
-  endif()
-
   target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
 endif()
 

Help/guide/tutorial/Step10/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
@@ -15,20 +13,13 @@ 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) {
+    std::cout << "Use the table to help find an initial value " << std::endl;
     result = sqrtTable[static_cast<int>(x)];
   }
 
-  // if we have both log and exp then use them
-
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
     if (result <= 0) {
@@ -38,7 +29,7 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-#endif
+
   return result;
 }
 }

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

@@ -40,10 +40,6 @@ if(USE_MYMATH)
   target_link_libraries(SqrtLibrary PUBLIC tutorial_compiler_flags)
 
   target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
-  if(HAVE_LOG AND HAVE_EXP)
-    target_compile_definitions(SqrtLibrary
-                               PRIVATE "HAVE_LOG" "HAVE_EXP")
-  endif()
   target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
 endif()
 

Help/guide/tutorial/Step11/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
@@ -15,20 +13,13 @@ 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) {
+    std::cout << "Use the table to help find an initial value " << std::endl;
     result = sqrtTable[static_cast<int>(x)];
   }
 
-  // if we have both log and exp then use them
-
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
     if (result <= 0) {

Help/guide/tutorial/Step7/MathFunctions/CMakeLists.txt

@@ -24,17 +24,6 @@ target_include_directories(MathFunctions
           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)

Help/guide/tutorial/Step7/MathFunctions/mysqrt.cxx

@@ -4,8 +4,6 @@
 // include the generated table
 #include "Table.h"
 
-#include <cmath>
-
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -16,6 +14,7 @@ double mysqrt(double x)
   // use the table to help find an initial value
   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)];
   }
 

Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt

@@ -24,17 +24,6 @@ target_include_directories(MathFunctions
           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)

Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx

@@ -4,8 +4,6 @@
 // include the generated table
 #include "Table.h"
 
-#include <cmath>
-
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -13,20 +11,13 @@ 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) {
+    std::cout << "Use the table to help find an initial value " << std::endl;
     result = sqrtTable[static_cast<int>(x)];
   }
 
-  // if we have both log and exp then use them
-
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
     if (result <= 0) {
@@ -36,6 +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;
 }

Help/guide/tutorial/Step9/MathFunctions/CMakeLists.txt

@@ -26,17 +26,6 @@ target_include_directories(MathFunctions
 # and that anything that links to use will get this define
 target_compile_definitions(MathFunctions INTERFACE "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)
-
-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)

Help/guide/tutorial/Step9/MathFunctions/mysqrt.cxx

@@ -4,8 +4,6 @@
 // include the generated table
 #include "Table.h"
 
-#include <cmath>
-
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -13,20 +11,13 @@ 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) {
+    std::cout << "Use the table to help find an initial value " << std::endl;
     result = sqrtTable[static_cast<int>(x)];
   }
 
-  // if we have both log and exp then use them
-
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
     if (result <= 0) {
@@ -36,6 +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;
 }

Help/guide/tutorial/index.rst

@@ -450,27 +450,29 @@ this step.
 Adding a Custom Command and Generated File (Step 6)
 ===================================================
 
-In this section, we will add a generated source file into the build process
-of an application. For this example, we will create a table of precomputed
-square roots as part of the build process, and then compile that
-table into our application.
+Suppose, for the purpose of this tutorial, we decide that we never want to use
+the platform ``log`` and ``exp`` functions and instead would like to
+generate a table of precomputed values to use in the ``mysqrt`` function.
+In this section, we will create the table as part of the build process,
+and then compile that table into our application.
 
-To accomplish this, we first need a program that will generate the table. In
-the MathFunctions subdirectory a new source file named ``MakeTable.cxx`` will
-do just that.
+First, let's remove the check for the ``log`` and ``exp`` functions in
+MathFunctions/CMakeLists. Then remove the check for ``HAVE_LOG`` and
+``HAVE_EXP`` from ``mysqrt.cxx``. At the same time, we can remove
+:code:`#include <cmath>`.
 
-.. literalinclude:: Step7/MathFunctions/MakeTable.cxx
-  :language: c++
+In the MathFunctions subdirectory, a new source file named ``MakeTable.cxx``
+has been provided to generate the table.
 
-Note that the table is produced as valid C++ code and that the output filename
-is passed in as an argument.
+After reviewing the file, we can see that the table is produced as valid C++
+code and that the output filename is passed in as an argument.
 
-The next step is to add the appropriate commands to MathFunctions' CMakeLists
+The next step is to add the appropriate commands to MathFunctions CMakeLists
 file to build the MakeTable executable and then run it as part of the build
 process. A few commands are needed to accomplish this.
 
-First, the executable for ``MakeTable`` is added as any other executable would
-be added.
+First, at the top of MathFunctions/CMakeLists, the executable for ``MakeTable``
+is added as any other executable would be added.
 
 .. literalinclude:: Step7/MathFunctions/CMakeLists.txt
   :language: cmake
@@ -509,10 +511,14 @@ Now let's use the generated table. First, modify ``mysqrt.cxx`` to include
   :start-after: // a hack square root calculation using simple operations
 
 Run **cmake** or **cmake-gui** to configure the project and then build it
-with your chosen build tool. When this project is built it will first build
-the ``MakeTable`` executable. It will then run ``MakeTable`` to produce
-``Table.h``. Finally, it will compile ``mysqrt.cxx`` which includes
-``Table.h`` to produce the MathFunctions library.
+with your chosen build tool.
+
+When this project is built it will first build the ``MakeTable`` executable.
+It will then run ``MakeTable`` to produce ``Table.h``. Finally, it will
+compile ``mysqrt.cxx`` which includes ``Table.h`` to produce the MathFunctions
+library.
+
+Run the Tutorial executable and verify that it is using the table.
 
 Building an Installer (Step 7)
 ==============================