Some Functions Computable with a Fused-mac

Sylvie Boldo (1) , Jean-Michel Muller (1)

1 ARENAIRE - Computer arithmetic

The fused multiply accumulate instruction (fused-mac) that is available on some current processors such as the Power PC or the Itanium eases some calculations. We give examples of some floating-point functions (such as ulp(x) or Nextafter(x,y)), or some useful tests, that are easily computable using a fused-mac. Then, we show that, with rounding to the nearest, the error of a fused-mac instruction is exactly representable as the sum of two floating-point numbers. We give an algorithm that computes that error.

Domaines: Analyse numérique [cs.NA]

Sylvie Boldo, Jean-Michel Muller. Some Functions Computable with a Fused-mac. 17th IEEE Symposium on Computer Arithmetic, Jun 2005, Cape Cod, Massachusetts, USA, pp.52-58. ⟨inria-00000895⟩