On executing the following code (compiled with g++ 4.6.3 on Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz running Ubuntu 12.04.1 LTS):

#include<cmath>
#include<stdio.h>
using namespace std;
int main()
{
 float f = 4386557896710122704971697171202048.0;
 printf("%.16f\n", tan(f));
 return 0;
}

I get the output as 33554432.0
The expected output is 97800744.0

In hex, this means libm says
tan(0x77584625) = 0x4C000000
However, the output should be 0x4CBA8A45.

The "correct" output was obtained using WolframAlpha
(97800745.2669871207241704332677514328806018068212018723832)
and one other compiler does produce the right output
(in hex 0x4CBA8A45, in decimal 97800744.0)
for the same program.

I know that the input is a bit strange, but looking at the hex
it seems to be a valid representable floating point number.
Using double instead of float makes the problem go away.