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# * downloaded Nov 2016 from https://android.googlesource.com/platform/external/eigen/+/master/cmake/FindStandardMathLibrary.cmake
# * changed CXX to C
# * note that full path to libm *not* detected
# - Try to find how to link to the standard math library, if anything at all is needed to do.
# On most platforms this is automatic, but for example it's not automatic on QNX.
#
# Once done this will define
#
# STANDARD_MATH_LIBRARY_FOUND - we found how to successfully link to the standard math library
# STANDARD_MATH_LIBRARY - the name of the standard library that one has to link to.
# -- this will be left empty if it's automatic (most platforms).
# -- this will be set to "m" on platforms where one must explicitly
# pass the "-lm" linker flag.
#
# Copyright (c) 2010 Benoit Jacob <jacob.benoit.1@gmail.com>
# Redistribution and use is allowed according to the terms of the 2-clause BSD license.
include(CheckCSourceCompiles)
# a little test program for c++ math functions.
# notice the std:: is required on some platforms such as QNX
set(find_standard_math_library_test_program
"#include<math.h>
int main() { sin(0.0); log(0.0f); }")
# C++ test program
# "#include<cmath>
# int main() { std::sin(0.0); std::log(0.0f); }")
# first try compiling/linking the test program without any linker flags
set(CMAKE_REQUIRED_FLAGS "")
set(CMAKE_REQUIRED_LIBRARIES "")
CHECK_C_SOURCE_COMPILES(
"${find_standard_math_library_test_program}"
standard_math_library_linked_to_automatically
)
if(standard_math_library_linked_to_automatically)
# the test program linked successfully without any linker flag.
set(STANDARD_MATH_LIBRARY "")
set(STANDARD_MATH_LIBRARY_FOUND TRUE)
else()
# the test program did not link successfully without any linker flag.
# This is a very uncommon case that so far we only saw on QNX. The next try is the
# standard name 'm' for the standard math library.
set(CMAKE_REQUIRED_LIBRARIES "m")
CHECK_C_SOURCE_COMPILES(
"${find_standard_math_library_test_program}"
standard_math_library_linked_to_as_m)
if(standard_math_library_linked_to_as_m)
# the test program linked successfully when linking to the 'm' library
set(STANDARD_MATH_LIBRARY "m")
set(STANDARD_MATH_LIBRARY_FOUND TRUE)
else()
# the test program still doesn't link successfully
set(STANDARD_MATH_LIBRARY_FOUND FALSE)
endif()
endif()
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