can't link against math.h

[blubee blubeeme]

I wrote a simple test program to test and see if math.h has the function:
exp10f

#include <math.h>

int main(int argc, char** argv)
{
(void)argv;
return ((int*)(&exp10))[argc];
}

tried compiling it with clang:
clang++ test.cpp -o test -lm
test.cpp:7:17: error: use of undeclared identifier 'expf10'
return ((int*)(&expf10))[argc];
                ^
1 error generated.

tried with gcc:
gcc test.cpp -o test -lm
test.cpp: In function 'int main(int, char**)':
test.cpp:7:17: error: 'expf10' was not declared in this scope
 return ((int*)(&expf10))[argc];

Does FreeBSD math.h have expf10 and if so, how do I link against it?