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Diffstat (limited to 'Help/guide/tutorial/Step8/MathFunctions')
6 files changed, 150 insertions, 0 deletions
diff --git a/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt new file mode 100644 index 0000000..872a24a --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/CMakeLists.txt @@ -0,0 +1,58 @@ +add_library(MathFunctions MathFunctions.cxx) + +# should we use our own math functions +option(USE_MYMATH "Use tutorial provided math implementation" ON) +if (USE_MYMATH) + target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH") + + # library that just does sqrt + add_library(SqrtLibrary STATIC + mysqrt.cxx + ) + + target_link_libraries(SqrtLibrary PUBLIC 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(SqrtLibrary + PRIVATE "HAVE_LOG" "HAVE_EXP" + ) + endif() + + target_link_libraries(MathFunctions PRIVATE SqrtLibrary) +endif() + +# state that anybody linking to us needs to include the current source dir +# to find MathFunctions.h, while we don't. +target_include_directories(MathFunctions + INTERFACE ${CMAKE_CURRENT_SOURCE_DIR} + ) + +# link our compiler flags interface library +target_link_libraries(MathFunctions PUBLIC tutorial_compiler_flags) + +# install libs +set(installable_libs MathFunctions tutorial_compiler_flags) +if(TARGET SqrtLibrary) + list(APPEND installable_libs SqrtLibrary) +endif() +install(TARGETS ${installable_libs} DESTINATION lib) +# install include headers +install(FILES MathFunctions.h DESTINATION include) diff --git a/Help/guide/tutorial/Step8/MathFunctions/MakeTable.cxx b/Help/guide/tutorial/Step8/MathFunctions/MakeTable.cxx new file mode 100644 index 0000000..ee58556 --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/MakeTable.cxx @@ -0,0 +1,25 @@ +// A simple program that builds a sqrt table +#include <cmath> +#include <fstream> +#include <iostream> + +int main(int argc, char* argv[]) +{ + // make sure we have enough arguments + if (argc < 2) { + return 1; + } + + std::ofstream fout(argv[1], std::ios_base::out); + const bool fileOpen = fout.is_open(); + if (fileOpen) { + fout << "double sqrtTable[] = {" << std::endl; + for (int i = 0; i < 10; ++i) { + fout << sqrt(static_cast<double>(i)) << "," << std::endl; + } + // close the table with a zero + fout << "0};" << std::endl; + fout.close(); + } + return fileOpen ? 0 : 1; // return 0 if wrote the file +} diff --git a/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.cxx b/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.cxx new file mode 100644 index 0000000..dc28b4b --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.cxx @@ -0,0 +1,19 @@ +#include "MathFunctions.h" + +#include <cmath> + +#ifdef USE_MYMATH +# include "mysqrt.h" +#endif + +namespace mathfunctions { +double sqrt(double x) +{ +// which square root function should we use? +#ifdef USE_MYMATH + return detail::mysqrt(x); +#else + return std::sqrt(x); +#endif +} +} diff --git a/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.h new file mode 100644 index 0000000..d5c2f22 --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/MathFunctions.h @@ -0,0 +1,5 @@ +#pragma once + +namespace mathfunctions { +double sqrt(double x); +} diff --git a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx new file mode 100644 index 0000000..28ab042 --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx @@ -0,0 +1,36 @@ +#include "mysqrt.h" + +#include <cmath> +#include <iostream> + +namespace mathfunctions { +namespace detail { +// a hack square root calculation using simple operations +double mysqrt(double x) +{ + if (x <= 0) { + return 0; + } + + // 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; + + // do ten iterations + for (int i = 0; i < 10; ++i) { + if (result <= 0) { + result = 0.1; + } + double delta = x - (result * result); + result = result + 0.5 * delta / result; + std::cout << "Computing sqrt of " << x << " to be " << result << std::endl; + } +#endif + return result; +} +} +} diff --git a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.h b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.h new file mode 100644 index 0000000..593d41e --- /dev/null +++ b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.h @@ -0,0 +1,7 @@ +#pragma once + +namespace mathfunctions { +namespace detail { +double mysqrt(double x); +} +} |