Is this a compiler bug?

[A Moore]

Using floats, floor() returns wrong result, as shown in this program:
( BTW, using gcc 4.0.1 )

#include <cmath>
#include <iostream>

int
main()
{

  float        x( 3.31682e-7 );
  float        y( -292.608 );
  float        z( 19.5072 );

  std::cout << "Using floats, floor() returns the wrong result:" << 
std::endl;
  std::cout << "( x - y ) / z : " << ( ( x - y ) / z ) << std::endl;
  std::cout << "floor of ( ( x - y ) / z ) : " << ::floor( ( x - y ) / 
z ) << std::endl;


  double        xx( 3.31682e-7 );
  double        yy( -292.608 );
  double        zz( 19.5072 );

  std::cout << "Using doubles, floor() works as expected:" << std::endl;
  std::cout << "( xx - yy ) / zz : " << ( ( xx - yy ) / zz ) << std::endl;
  std::cout << "floor of ( ( xx - yy ) / zz ) : " << ::floor( ( xx - yy 
) / zz ) << std::endl;

  return 0;

}