GNU Scientific Library - Bugs: bug #40092, false position root finding...
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bug #40092: false position root finding requires too many function evals
Submitter: | Patrick Alken <psa> | ||
Submitted: | Mon 23 Sep 2013 03:49:24 PM UTC | ||
Category: | Performance | Severity: | 3 - Normal |
Operating System: | Status: | Postponed | |
Assigned to: | None | Open/Closed: | Open |
Release: |
Sat 05 Oct 2013 08:37:39 AM UTC, comment #5: |
Max <nikulin> |
Sat 05 Oct 2013 07:39:29 AM UTC, comment #4: Thank you for your further input.
|
Brian Gladman <gladman> |
Sat 05 Oct 2013 05:35:22 AM UTC, comment #3: I would like to stress the point from the original message.
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Max <nikulin> |
Sat 05 Oct 2013 05:20:09 AM UTC, comment #2: Brian,
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Max <nikulin> |
Thu 03 Oct 2013 01:16:34 PM UTC, comment #1: Running the supplied program on Windows x64 gives:
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Brian Gladman <gladman> |
Mon 23 Sep 2013 03:49:24 PM UTC, original submission:
From M.A.Nikulin@gmail.com:
|
Patrick Alken <psa> |
Depends on the following items: None found
Items that depend on this one: None found
Follow 3 latest changes.
Date | Changed by | Updated Field | Previous Value | => | Replaced by |
---|---|---|---|---|---|
2013-10-05 | gladman | Status | Works For Me | Postponed | |
2013-10-05 | nikulin | Attached File | - | Added gsl-falsepos64.c, #29298 | |
2013-10-03 | gladman | Status | None | Works For Me |
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Corresponding source code
The quick fix may be to check that x_linear differs
from x_left and x_right by some value. Some multiple of
GSL_DBL_EPSILON since required precision is not available
by design.
I do not think that additional tests of function values
may help since the derivative of the function can
be arbitrary large or small close to the root: 1e9*(x - 1)
or 1e-9*(x - 1).
That is why I tried to raise discussion on gsl-help
instead of reporting a bug.