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Re: Same .m file: different results with different versions of Octave
From: |
Judd Storrs |
Subject: |
Re: Same .m file: different results with different versions of Octave |
Date: |
Wed, 21 Apr 2010 00:49:05 -0400 |
I've started the attached program to test the accuracy and speed of
ctanh implementations.
One thing I realized is that the x=22 cutoff only applies to the real
component. Being eps from zero means nothing (doh) so I need to rework
the overflow of the denominator for the imaginary component.
The testing code uses MPFR and evaluates a grid (see top of file for
#defines to configure--sorry no fancyness). At each point it tests
whether the libm ctanh is within a multiple of eps from the MPFR
value. Compile with
c99 -o ctanh_test -lm -lmpfr ctanh_test.c
I intend to tests for the C99 special cases. Here are some results:
Original glibc:
Error magn Real part Imag part Both
----------- ---------- ---------- ---------
>= 1 eps 11146 7376 6296
>= 2 eps 296 290 2248
>= 3 eps 48 150 1500
>= 4 eps 24 128 1156
>= 5 eps 32 86 952
>= 6 eps 8 68 788
>= 7 eps 36 64 692
>= 8 eps 12 54 604
>= 9 eps 8 56 544
>=10 eps 12 52 472
Grid size: 1025 x 1025
Top Left corner: -8.000000 + +8.000000 i
Bottom Right corner: +8.000000 + -8.000000 i
Time to evaluate grid: 131.340000 (sec) [10000 loops]
Internal inconsistencies: 0
This is a stripped down version of the Jaroslav's optimized version
(removing all branches for now):
Error magn Real part Imag part Both
----------- ---------- ---------- ---------
>= 1 eps 12990 71680 6208
>= 2 eps 0 4 0
>= 3 eps 0 0 0
>= 4 eps 0 0 0
>= 5 eps 0 0 0
>= 6 eps 0 0 0
>= 7 eps 0 0 0
>= 8 eps 0 0 0
>= 9 eps 0 0 0
>=10 eps 0 0 0
Grid size: 1025 x 1025
Top Left corner: -8.000000 + +8.000000 i
Bottom Right corner: +8.000000 + -8.000000 i
Time to evaluate grid: 134.570000 (sec) [10000 loops]
Internal inconsistencies: 0
One thing you will notice is that the new code generates more total
errors but they are all small ~1eps. On the other hand, the old code
has quite a few errors greater than 10 eps. It could be that the
floating point rounding mode I chose for MPFR doesn't match what the
ieee doubles are doing. Also, notice that the change in cpu time is
very small with Jaroslav's optimizations.
--judd
ctanh_test.c
Description: Text Data
- Re: Same .m file: different results with different versions of Octave, (continued)
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/20
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/20
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/20
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/20
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/20
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/20
- Re: Same .m file: different results with different versions of Octave,
Judd Storrs <=
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Ozzy Lash, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Judd Storrs, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/22
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/21
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/21