I've found a worrying rounding error which is manifested by the
following simple test program.
I ran this on linux2.0.26, and compiled with gcc version 2.7.2
double d1 = 2.4,
d2 = 1000,
d3;
func1( double val )
{
printf( "%ld\n", (long) val );
}
func( long val )
{
printf( "%ld\n", val );
}
main()
{
d3 = d1 * d2;
printf( "func( (long) d3 ) -> " );
func( (long) d3 );
printf( "func( (long) (d1 * d2) ) -> " );
func( (long) (d1 * d2) );
printf( "func1( d1 * d2 ) -> " );
func1( d1 * d2 );
}
This produced:
func( (long) d3 ) -> 2400
func( (long) (d1 * d2) ) -> 2399
func1( d1 * d2 ) -> 2400
The second line of output manifests the rounding problem.
I compiled and ran exactly the same program on Non-StopUX with the
native C compiler and Win98 using M$ 32-bit compiler version
10.20.6166 which both produced the correct value on the second
output line.
Would anyone like to comment?
Andy
aml@bsl.co.uk
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