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Bug 379234 - Goalseeker does not work properly;solver cannot accept constraints
Goalseeker does not work properly;solver cannot accept constraints
Status: RESOLVED FIXED
Product: Gnumeric
Classification: Applications
Component: Analytics
unspecified
Other All
: Normal normal
: ---
Assigned To: Morten Welinder
Jody Goldberg
Depends on:
Blocks:
 
 
Reported: 2006-11-25 18:22 UTC by Anatoly Khmelnitsky
Modified: 2006-11-27 01:26 UTC
See Also:
GNOME target: ---
GNOME version: ---


Description Anatoly Khmelnitsky 2006-11-25 18:22:29 UTC 
Goalseeker cannot resolve simple equation x^2-2*x+1 ( or x^2-6*x+9)

I have tried to do this work with solver. But it cannot resolve equation without
constraints. So when I need to add constraint (something as -2<=x<=2)  - I was stacked
Comment 1 Morten Welinder 2006-11-26 14:08:09 UTC 
The goal seeker is messed up.  I'm on the case.
Comment 2 Morten Welinder 2006-11-27 01:26:02 UTC 
Fixed in the development version. The fix will be available in the next major release. Thank you for your bug report.


Note, in both cases shown we have a root of multiplicity 2.  That has two
consequences:

1. Newton iteration converges much slower.

2. Bisection methods won't work here since the graph does not pass through
   zero, but just touches.

I allowed more Newton iterations and a root is now found.  It does not
have impressive accuracy, but I would like to setup a fully automatic
test suite before I change anything major in there.