Re: [Help-glpk] [Fwd: Scaling: Which? and Suppressing output]

[glpk xypron]

Hello Glenn,

your e-mail did not reach the GLPK help list directly, because
you did not register. See
http://lists.gnu.org/mailman/listinfo/help-glpk

> A: min|aij| =  4.000e-01  max|aij| =  2.800e+00  ratio =  7.000e+00
> Problem data seem to be well scaled
The message is written in file glpk-4.45/src/glpscl.c
You could replace the following lines:

      if (min_aij >= 0.10 && max_aij <= 10.0)
      {  xprintf("Problem data seem to be well scaled\n");
         /* skip scaling, if required */
         if (flags & GLP_SF_SKIP) goto done;
      }

Best regards

Xypron



> -------- Forwarded Message --------
> Subject: Scaling: Which? and Suppressing output
> Date: Thu, 24 Feb 2011 11:38:50 -0500
> 
> Hi,
> 
> I have a C++ application where calling glpk_simplex() sometimes
> generates a "numerical instability" warning message.  To fix this
> problem, I tried to scale the data by first calling glpk_scale_prob().
>  However, calling glpk_scale_prob() generally prints out a message like
> 
> 
> A: min|aij| =  4.000e-01  max|aij| =  2.800e+00  ratio =  7.000e+00
> Problem data seem to be well scaled
> 
> This is especially annoying because in this application, I am solving
> *millions* or even billions of very small dense LPs (these LPs come
> from matrix games).  How can I suppress these messages and still get
> any warning or error messages that I need to see?  Right now, any
> warning messages are getting lost in a never-ending stream of useless
> messages.
> 
> 
> Also, there are a couple of different scaling options available such as
> "geometric mean" scaling and "equilibration" scaling.  I don't know
> what these are.  Are there any useful rules of thumb as to which
> scaling method to use?
> 
> -- Glenn C. Rhoads
> 
> 
> 
> 
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