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[Octave-bug-tracker] [bug #53140] Solution of a system of linear equatio
From: |
Rik |
Subject: |
[Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance. |
Date: |
Mon, 19 Feb 2018 13:19:26 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 |
Follow-up Comment #12, bug #53140 (project octave):
After some more debugging, there is definitely a problem here.
I instrumented the code to be
octave_idx_type sz = x_nz * (b_nc - j) / b_nc;
std::cerr << "sz: " << sz << std::endl;
std::cerr << "x_nz: " << x_nz << std::endl;
sz = (sz > 10 ? sz : 10) + x_nz;
std::cerr << "before change_capacity" << std::endl;
retval.change_capacity (sz);
std::cerr << "after change_capacity" << std::endl;
x_nz = sz;
std::cerr << "new sz: " << sz << std::endl;
And when running, I see that the size argument goes negative because
octave_idx_type is a sized value, but I can't see why we would ever want to
change the capacity of the sparse matrix to a negative value.
Runtime results:
resizing sparse matrix
sz: -2031109
x_nz: 3519011
before change_capacity
after change_capacity
new sz: 3519021
sz: -2031102
x_nz: 3519021
before change_capacity
after change_capacity
new sz: 3519031
sz: -2031094
x_nz: 3519031
before change_capacity
after change_capacity
new sz: 3519041
sz: -2031086
x_nz: 3519041
As you can see, the overall size keeps going up by just 10 values which means
it takes many iterations before the sparse matrix is increased sufficiently in
size.
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- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., (continued)
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., John W. Eaton, 2018/02/13
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., John W. Eaton, 2018/02/13
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/13
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/14
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/15
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/15
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/16
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/18
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/19
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/19
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance.,
Rik <=
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/19
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/19
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/20
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/20
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/21
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/23
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., John W. Eaton, 2018/02/23
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Rik, 2018/02/26
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., Marco Caliari, 2018/02/27
- [Octave-bug-tracker] [bug #53140] Solution of a system of linear equations takes forever and hurts OS performance., John W. Eaton, 2018/02/27