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[Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse respo
From: |
Mike Miller |
Subject: |
[Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64 |
Date: |
Fri, 11 May 2018 16:49:23 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 |
URL:
<http://savannah.gnu.org/bugs/?53881>
Summary: [octave forge] (control) impulse response differs
greatly on i386 vs x86_64
Project: GNU Octave
Submitted by: mtmiller
Submitted on: Fri 11 May 2018 01:49:22 PM PDT
Category: Octave Forge Package
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Inaccurate Result
Status: None
Assigned to: None
Originator Name:
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: dev
Operating System: GNU/Linux
_______________________________________________________
Details:
The impulse response of a simple system is very inaccurate when comparing the
results on X86-32 (i386) to the results on X86-64.
I run the following script on a 32-bit Octave 4.4 with control 3.1.0
pkg load control
sys = tf ([1, 1], [1, 2, 1]);
y = impulse (sys, [0:99] ./ 100).';
save results32.txt
and the following script on a 64-bit Octave 4.4 with control 3.1.0
pkg load control
sys = tf ([1, 1], [1, 2, 1]);
y = impulse (sys, [0:99] ./ 100).';
results32 = load ('results32.txt');
fprintf (stdout, '%4u %-17.15g %-17.15g\n', [0:99; results32.y; y]);
and I get the following output. Even at the start of the impulse response the
vectors are accurate to only three decimal places. By the end the accuracy is
down to one decimal place.
0 1 1
1 0.998999167089151 0.999007621746616
2 0.997999335844817 0.998016228307829
3 0.997000505264498 0.997025818706332
4 0.996002674346696 0.996036391965785
…
250 0.778541081031692 0.780190040994487
251 0.777761891495348 0.779415797364297
252 0.776983481797535 0.778642322076649
253 0.776205851157766 0.777869614369055
254 0.775428998796333 0.777097673479787
…
500 0.606126214853996 0.60869650006698
501 0.605519583790042 0.608092442897402
502 0.604913559862421 0.607488985181024
503 0.604308142463491 0.60688612632296
504 0.60370333098622 0.606283865728916
…
995 0.369232996221608 0.372355352593404
996 0.368863455687218 0.371985835238959
997 0.368494285001156 0.371616684585501
998 0.368125483793267 0.371247900269124
999 0.367757051693765 0.370879481926282
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?53881>
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- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64,
Mike Miller <=
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Mike Miller, 2018/05/11
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Mike Miller, 2018/05/11
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Doug Stewart, 2018/05/12
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Mike Miller, 2018/05/12
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Mike Miller, 2018/05/12
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Doug Stewart, 2018/05/12
- [Octave-bug-tracker] [bug #53881] [octave forge] (control) impulse response differs greatly on i386 vs x86_64, Doug Stewart, 2018/05/12