bugGNU Scientific Library - Bugs: bug #23192, Nelder Mead bug in finding second...

 
 

You are not allowed to post comments on this tracker with your current authentication level.

bug #23192: Nelder Mead bug in finding second highest point

Submitter:  -Deleted Account- <bjg>
Submitted:  Tue 06 May 2008 08:57:01 PM UTC
   
 
Category:  Runtime error Severity:  3 - Normal
Operating System:  Status:  Fixed
Assigned to:  bjg Open/Closed:  Closed
Release:  1.11

Tue 06 May 2008 09:01:49 PM UTC, comment #1: 

fixed by 84ab11b5350babde3e57576a98f5c14a4d1278fd

-Deleted Account- <bjg>
Tue 06 May 2008 08:57:01 PM UTC, original submission:  

From: "Michael Kuklik" <mkuklik@gmail.com>
To: -email is unavailable-
Subject: [Bug-gsl] Nelder Mead bug
Date: Sun, 4 May 2008 21:23:27 -0400

Hi everyone,

Nelder Mead , i.e. simplex search has a bug. In the function
static int
nmsimplex_iterate (void vstate, gsl_multimin_function f,
                   gsl_vector * x, double *size, double *fval)

in multimin/simplex.c
a piece of code that determines the highest , second highest and lowest
vertex fails when first value in y1 is the highest.
It returns second highest equal to the highest. Later that influence
decision in the algorithm.

FIX:
add lines:
  ds_hi = gsl_vector_get (y1, 1);
  s_hi = 1;
before the loop

CODE SHOULD LOOK LIKE THIS:

...
 if (xc->size != x->size)
    {
      GSL_ERROR("incompatible size of x", GSL_EINVAL);
    }

  /* get index of highest, second highest and lowest point */

  dhi = ds_hi = dlo = gsl_vector_get (y1, 0);
  ds_hi = gsl_vector_get (y1, 1);
  s_hi = 1;
  for (i = 1; i < n; i++)
    {
      val = (gsl_vector_get (y1, i));
      if (val < dlo)
        {
          dlo = val;
          lo = i;
        }
...

Cheers,

Michal Kuklik
_____________________________________________
Bug-gsl mailing list
-email is unavailable-
http://lists.gnu.org/mailman/listinfo/bug-gsl


-Deleted Account- <bjg>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

No files currently attached

 

Depends on the following items: None found

Items that depend on this one: None found

 

CC list is empty

 

Follow 2 latest changes.

Date Changed by Updated Field Previous Value => Replaced by
2008-05-06 bjg StatusConfirmed Fixed
    Open/ClosedOpen Closed

Back to the top

Powered by Savane 3.13-f8d8.
Corresponding source code