fails with FPU set to single precision
spitzak at d2.com
Thu Aug 31 13:10:55 PDT 2006
Fabien Costantini wrote:
> Well epsilon seems useful this time because it will bug otherwise if
> values are between [1.0-1.e-20,1.0[
> i.e: the following example:
> int v = (int) ((1.0-1.e-20)*65536);
> printf("val = %d\n",v);
> returns 65536
In 64-bit doubles, 1-1e-20 is not any different from 1.0. This prints 0
on my machine:
double f = 1.0-1e-20;
So the code that says "if (f<1) return 65536*f; else return 65535;"
works because it takes the second case.
In fact any numbers closer than 5.55111512313e-17 (2^-54) to 1.0 are 1.0
in IEEE 64-bit floats.
More information about the cairo