[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Same .m file: different results with different versions of Octave
From: |
Thomas D. Dean |
Subject: |
Re: Same .m file: different results with different versions of Octave |
Date: |
Mon, 19 Apr 2010 11:47:54 -0700 |
On Mon, 2010-04-19 at 11:05 -0700, Søren Hauberg wrote:
> I don't understand why
>
> (inf + inf * i) / (inf + inf * i)
>
> should equal
>
> 1 + 0 * i.
>
> I can understand why the 'tanh' call should give this result, but once
> you actually evaluate 'sinh' and 'cosh' and perform the division
> manually I don't see why you should get 1.
>
> Could you elaborate on this?
I copied the code and made the output modifications to emulate the c++
code. I think the output of sin()/cos() should be 1 + 0 * i, not the
(inf... values.
The library seems to have some problems with over/under flow detection,
I believe.
I tried to build eglibc (ubuntu special version of glibc) and failed.
This was from using apt-get source, configure, and make. Undefined
reference to __sync_fetch_and_add_4, etc. This looks like a gcc
builtin???
If I change to use long double everywhere, creall, cimagl, %Lf, etc., I
greatly extend the range to have 5678*(1+i) correct and 5679*(1+i)
failing. The output is symetrical about zero as -5678 is correct and
-5679 failing.
This is still an over/under flow problem as
limit(n*(1+i),n=infinity) == 1
I believe tanh should never return nan + 0*i with complex, non-nan and
non-inf arguments.
- Re: Same .m file: different results with different versions of Octave, (continued)
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Søren Hauberg, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/19
- 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, Judd Storrs, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Jaroslav Hajek, 2010/04/19
- 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, Judd Storrs, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Søren Hauberg, 2010/04/19
- Re: Same .m file: different results with different versions of Octave,
Thomas D. Dean <=
- Re: Same .m file: different results with different versions of Octave, Søren Hauberg, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Søren Hauberg, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/19
- Re: Same .m file: different results with different versions of Octave, Thomas D. Dean, 2010/04/19
- 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, 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