[Scipy-tickets] [SciPy] #1286: Incorrect result returned by optimize.fixed_point

SciPy Trac scipy-tickets@scipy....
Sat Sep 25 20:11:42 CDT 2010


#1286: Incorrect result returned by optimize.fixed_point
-----------------------------------+----------------------------------------
 Reporter:  warren.weckesser       |       Owner:  somebody
     Type:  defect                 |      Status:  new     
 Priority:  normal                 |   Milestone:  0.9.0   
Component:  scipy.optimize         |     Version:  devel   
 Keywords:  fixed_point, optimize  |  
-----------------------------------+----------------------------------------
 For the function f(x)=x**2, with an initial guess of, for example, 1.05,
 scipy.optimize.fixed_point returned 1.0044..., which does not meet the
 default tolerance of 1e-8.  The problem is that the test of the stopping
 condition in the implementation of Steffensen's algorithm does not take
 the absolute value of the relative error when it compares it to the
 tolerance.

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Ticket URL: <http://projects.scipy.org/scipy/ticket/1286>
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