I have had a bug report from people who tested my gfortran binaries for mingw-w64 that the float variants of math functions aren't working properly. The proper report that was sent to me has this example:

C:\gfortran\test\single_bug>type table.f90
program table
  real x
  integer i
  write(*,*) '   x     sin(x)    cos(x)   tan(x)'
  do i = 0, 10
     x = i
     write(*,*) x, sin(x), cos(x), tan(x)
  end do
end program table

C:\gfortran\test\single_bug>c:\gfortran\win64\bin\x86_64-pc-mingw32-gfortran table.f90 -o table

C:\gfortran\test\single_bug>table
   x     sin(x)    cos(x)   tan(x)
  0.000000       0.000000       0.000000       0.000000
  1.000000       1.000000       1.000000       1.000000
  2.000000         2.0000         2.0000         2.0000
  3.000000         3.0000         3.0000         3.0000
  4.000000         4.0000         4.0000         4.0000
  5.000000         5.0000         5.0000         5.0000
  6.000000         6.0000         6.0000         6.0000
  7.000000         7.0000         7.0000         7.0000
  8.000000         8.0000         8.0000         8.0000
  9.000000         9.0000         9.0000         9.0000
  10.00000        10.0000        10.0000        10.0000


Indeed, there is a difference between a C function that calls sinf():

#include <math.h>
float foo(float *x) { return sinf(*x); }

which is compiled into:

_foo:
LFB47:
        pushq   %rbp
LCFI0:
        movq    %rsp, %rbp
LCFI1:
        subq    $32, %rsp
LCFI2:
        movq    %rcx, 16(%rbp)
        movq    16(%rbp), %rax
        movss   (%rax), %xmm0
        call    _sinf
        leave
        ret

and the equivalent Fortran function:

  real function foo(x)
    real x
    foo = sin(x)
  end function foo

that is compiled into:


_foo_:
LFB2:
        pushq   %rbp
LCFI0:
        movq    %rsp, %rbp
LCFI1:
        subq    $64, %rsp
LCFI2:
        movq    %rcx, 16(%rbp)
        movq    16(%rbp), %rax
        movss   (%rax), %xmm0
        call    _sinf
        movss   %xmm0, -4(%rbp)
        movl    -4(%rbp), %eax
        movl    %eax, -20(%rbp)
        movss   -20(%rbp), %xmm0
        leave
        ret

(Notice the extra lines between the call to _sinf and the leave.)