link to libm if necessary

src/CMakeLists.txt

@@ -24,7 +24,28 @@ set(HEADER_FILES    conv.h
                     )
 
 add_library(wavelib STATIC ${SOURCE_FILES} ${HEADER_FILES})
-        
+
+include(CheckSymbolExists)
+
+# https://stackoverflow.com/questions/32816646/can-cmake-detect-if-i-need-to-link-to-libm-when-using-pow-in-c
+if(NOT POW_FUNCTION_EXISTS AND NOT NEED_LINKING_AGAINST_LIBM)
+    check_symbol_exists(pow "math.h" POW_FUNCTION_EXISTS)
+    if(NOT POW_FUNCTION_EXISTS)
+        unset(POW_FUNCTION_EXISTS CACHE)
+        list(APPEND CMAKE_REQUIRED_LIBRARIES m)
+        check_symbol_exists(pow "math.h" POW_FUNCTION_EXISTS)
+        if(POW_FUNCTION_EXISTS)
+            set(NEED_LINKING_AGAINST_LIBM True CACHE BOOL "" FORCE)
+        else()
+            message(FATAL_ERROR "Failed making the pow() function available")
+        endif()
+    endif()
+endif()
+
+if(NEED_LINKING_AGAINST_LIBM)
+    target_link_libraries(wavelib PUBLIC m)
+endif()
+
 set_property(TARGET wavelib PROPERTY FOLDER "lib")
 
 target_include_directories(wavelib PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}../header)