python - f2py erf function lnk2019 unresolved external symbol error -

i trying use f2py command :

c:\python27\python.exe setup.py build_ext --inplace --fcompiler=g95 

my fortran file :

module test_f90  implicit none  real *8 :: delta  contains  subroutine test_f(val, r)     real*8, intent(out) :: val     real*8, intent(in)  :: r     val = 0.5*( 1 + erf(r/delta) ) end subroutine  end module test_f90 

but have got error :

test_fmod.o : error lnk2019: unresolved external symbol __g95_erf_r8 rÚfÚrencÚ d ans la fonction _test_f90_mp_test_f _test_f90.pyd : fatal error lnk1120: 1 externes non rÚsolus error: command "c:\program files (x86)\microsoft visual studio 9.0\vc\bin\link.e xe /dll /nologo /incremental:no /libpath:c:\python27\libs /libpath:c:\python27\p cbuild /libpath:c:\python27\pc\vs9.0 /libpath:c:\python27\libs /libpath:c:\pytho n27\pcbuild /libpath:c:\python27\pc\vs9.0 /export:init_test_f90 build\temp.win32 -2.7\release\build\src.win32-2.7\_test_f90module.obj build\temp.win32-2.7\releas e\build\src.win32-2.7\fortranobject.obj build\temp.win32-2.7\release\test_fmod.o  build\temp.win32-2.7\release\build\src.win32-2.7\_test_f90-f2pywrappers2.o /out :_test_f90.pyd /implib:build\temp.win32-2.7\release\build\src.win32-2.7\_test_f9 0.lib /manifestfile:build\temp.win32-2.7\release\build\src.win32-2.7\_test_f90.p yd.manifest" failed exit status 1120 

if substitute line val = 0.5*( 1 + erf(r/delta) ) val = 0.5*( 1 + sin(r/delta) ) f2py works well. problem due erf function don't know why. thought sin , erf same kind of function?