Denormal numbers

  • Author or source: Compiled by Merlijn Blaauw
  • Created: 2002-01-17 03:06:39
  • Linked files: other001.txt.
 this text describes some ways to avoid denormalisation. Denormalisation happens when
FPU's go mad processing very small numbers


See also the entry about 'branchless min, max and clip' by Laurent Soras in this section,

Using the following function,

float clip (float x, float a, float b)
   x1 = fabs (x-a);
   x2 = fabs (x-b);
   x = x1 + (a+b);
   x -= x2;
   x *= 0.5;
   return (x);

If you apply clipping from -1.0 to 1.0 will have a side effect of squashing denormal numbers to zero due to loss of precision on the order of ~1.0.e-20.  The upside is that it is branchless, but possibly more expensive than adding noise and certainly more so than adding a DC offset.