Re: [Help-glpk] [Fwd: Error - negative iteration limit]

[sheetal murkute]

Hi,

If I run the code for one of the data-sets again, I could run it successfully.

However, this is random. error still occurs for 2-3 datasets.

For iteration limit, I am calculating average of all simplex iterations (gamma_avg) required to solve the LP

at each node. I calculate this as follows. I also use gamma_avg = abs(gamma_avg) in the end.

For calculating LP relaxations at child nodes, I use iterations limit as (2*gamma_avg).

This value is becoming negative somewhere. This occurs only for 2 to 3 datasets out of 20. 

***********************************************************

variable declaration (global):

static int mynodeindex = 0,tot_it_count=0,num_node=0,gamma_avg=500;

***********************************************

Calculating average simplex iterations in callback routine:

case GLP_IBRANCH:

iter_count = lpx_get_int_parm(glp_ios_get_prob(tree), LPX_K_ITCNT);

if(iter_count > 0)

{

num_node = num_node+1;

tot_it_count = tot_it_count + iter_count;

tempitlim = tot_it_count / num_node;

gamma_avg = (int)tempitlim;

}

gamma_avg = abs(gamma_avg);

************************************************

Use 2*gamma_avg as iteration limit.

glp_init_smcp(&simplexparm2);

simplexparm2.it_lim = 2*gamma_avg;

Let me know if I am wrong somewhere.

Thanks,

Sheetal

On Sat, Jan 14, 2012 at 8:02 AM, glpk xypron <address@hidden> wrote:

Hello Sheetal,

please, subscribe to the help list. Otherwise your mails have
to be forwarded manually.
https://lists.gnu.org/mailman/listinfo/help-glpk

How can your problem be reproduced?

Best regards

Xypron

> -------- Forwarded Message --------
> From: sheetal murkute <address@hidden>
> To: address@hidden, Andrew Makhorin <address@hidden>
> Subject: Re: Error - negative iteration limit
> Date: Fri, 13 Jan 2012 15:51:56 -0500
>
> Furthermore, I have displayed last few lines in the log file below when
> I get negative iteration limit error.
>
> +184153: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16051;
> 2956)
> +184223: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16055;
> 2961)
> +184309: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16059;
> 2966)
> +184390: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16066;
> 2968)
> +184492: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16066;
> 2974)
> +184594: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16068;
> 2978)
> Time used: 12257.2 secs.  Memory used: 103.7 Mb.
> +184671: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16069;
> 2983)
> +184741: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16072;
> 2985)
> +184822: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16075;
> 2990)
> +184918: mip =   2.075400000e+05 >=   2.025778983e+05   2.4% (16078;
> 2995)
> +185113: mip =   2.075400000e+05 >=   2.027808401e+05   2.3% (16080;
> 3008)
> +185364: mip =   2.075400000e+05 >=   2.027808401e+05   2.3% (16093;
> 3022)
> glp_simplex: it_lim = -188940; invalid parameter
> Error detected in file glpapi06.c at line 403
>
>
>
> On Fri, Jan 13, 2012 at 3:49 PM, sheetal murkute <address@hidden>
> wrote:
>         Hi,
>
>
>         I have implemented strong branching for 20 datasets. For three
>         of these datasets,
>         My code gets terminated with error.
>         The message displayed in the log file is as follows.
>
>
>         glp_simplex: it_lim = -188940; invalid parameter
>         Error detected in file glpapi06.c at line 403
>
>
>         I have given iteration limit for calculating LP relaxation of
>         the child nodes. I have set this limit to positive value only.
>         I have not provided any simplex iteration limit elsewhere.
>
>         Can you please guide where this garbage negative value can come
>         from?
>
>
>
>
>
>
>         --
>         Thanks with Best Regards,
>         Sheetal
>
>
>
>
>
>
> --
> Thanks with Best Regards,
> Sheetal
>

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--
Thanks with Best Regards,
Sheetal

:)