[Scipy-tickets] [SciPy] #1198: optimize.bisection conditional test incorrect

SciPy Trac scipy-tickets@scipy....
Tue Jun 15 14:19:55 CDT 2010


#1198: optimize.bisection conditional test incorrect
---------------------------------+------------------------------------------
 Reporter:  brownnr              |       Owner:  somebody
     Type:  defect               |      Status:  new     
 Priority:  low                  |   Milestone:  0.8.0   
Component:  Other                |     Version:  0.7.0   
 Keywords:  optimize, bisection  |  
---------------------------------+------------------------------------------

Old description:

> In scipy version 0.8.0b1 scipy.optimize.bisection() in minpack.py, the
> conditional test for the bisection method is incorrect.
>
> The first few lines read
> i = 1
> eva = func(a, *args)
> evb = func(b, *args)
> if eva*evb < 0:
>   msg "Must start with interval where func(a) * func(b) < 0"
>   raise ValueError(msg)
>

> But the function does meet that condition by the conditional statement
> given, so it should be negated or
>
> if eva*evb >= 0:

New description:

 In scipy version 0.8.0b1 scipy.optimize.bisection() in minpack.py, the
 conditional test for the bisection method is incorrect.

 The first few lines read
 {{{
 i = 1
 eva = func(a, *args)
 evb = func(b, *args)
 if eva*evb < 0:
   msg "Must start with interval where func(a) * func(b) < 0"
   raise ValueError(msg)
 }}}

 But the function does meet that condition by the conditional statement
 given, so it should be negated or
 {{{
 if eva*evb >= 0:
 }}}

--

Comment(by warren.weckesser):

 Quote code in the description.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1198#comment:2>
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