Re: mathlib pow gives bad result
Re: mathlib pow gives bad result
- Subject: Re: mathlib pow gives bad result
- From: Tomas Zahradnicky <email@hidden>
- Date: Fri, 19 May 2006 14:57:36 +0200
If Itanium2 does x86 floating point arithmetic, keep in mind that x86
operates on 80 bit floats internally, while ppc (afaik) does "only" work
with the given 64 bit.
I believe that this depends on the mathlib implementation. Some
mathlibs such as fdlibm calculate results bit by bit and use integers
that they obtain by extracting mantissa from double and extending it
to 64 bits thus they obtain internal 80bit precision anyway.
So this probably is an architecture issue. You could try and compare
this to linux/ppc results (via a ppc/linux live-cd perhaps). If
precision is a general problem for you, you might try some software
implemented multi-precision floating point numbers, e. g. gmp [1].
By the way GMP 4.2.1 does not compile on itanium2 hp-ux I have :)
Tomas
--
# Ing. Tomas Zahradnicky, Jr.
# The Czech Technical University
# Dept of Computer Science, FEE-CTU Prague
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