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Re: [Help-glpk] proposal for gnu lp/mip low-level format
From: |
Brady Hunsaker |
Subject: |
Re: [Help-glpk] proposal for gnu lp/mip low-level format |
Date: |
Thu, 22 Jul 2004 10:18:17 -0400 |
This is certainly better than MPS format and is consistent with some
other common low-level formats. The ability to give row and column
names is good.
The one thing I would add is some guidelines about precision and
numerical formats. Is arbitrary precision allowed in the numbers? I
guess the idea would be that numbers would be rounded (as always) to fit
in whatever floating-point data type that a solver uses, but with no
predefined precision limit in the file. Therefore it is possible that
different solvers would round input differently if they use different
floating-point data types.
Also, I would perhaps make it explicit that various notations are
allowed:
-230.7
1.555e-07
What about slightly odd notations?
2.3e0004 (lots of unnecessary digits in the exponent)
231.3e7 (abnormal use of exponent)
Are real number input formats standardized anywhere? I have a sense of
what's "normal" and what isn't, but I don't know if it's written down
anywhere. This is important because we don't want some parsers to fail
on certain input files just because they disagreed on whether a format
was acceptable.
Brady
On Wed, 2004-07-21 at 21:30, Andrew Makhorin wrote:
> I propose a (GNU) low-level format for coding lp/mip instances. Below
> here is its brief description. I would appreciate any suggestions.
>
> Andrew Makhorin
>
>
> It is a text format. The file may contain the following lines:
>
> * comment
>
> N problem-name
>
> P problem-class objective-sense num-rows num-cols num-nz
>
> R row-num F
> R row-num L lower-bound
> R row-num U upper-bound
> R row-num D lower-bound upper-bound
> R row-num S fixed-value
>
> C col-num F
> C col-num L lower-bound
> C col-num U upper-bound
> C col-num D lower-bound upper-bound
> C col-num S fixed-value
>
> F col-num objective_coef
> F 0 constant-term
>
> A row-num col-num constraint-coefficient
>
> I row-num row-name
>
> J col-num col-name
>
> E O F
>
> All lines, except P-line and E-line, are optional and may follow in
> arbitrary order.
>
- [Help-glpk] proposal for gnu lp/mip low-level format, Andrew Makhorin, 2004/07/21
- Re: [Help-glpk] proposal for gnu lp/mip low-level format,
Brady Hunsaker <=
- Re: [Help-glpk] proposal for gnu lp/mip low-level format, Michael Hennebry, 2004/07/22
- Re[2]: [Help-glpk] proposal for gnu lp/mip low-level format, Andrew Makhorin, 2004/07/23
- Re[2]: [Help-glpk] proposal for gnu lp/mip low-level format, Michael Hennebry, 2004/07/27
- Re[3]: [Help-glpk] proposal for gnu lp/mip low-level format, Andrew Makhorin, 2004/07/28
- Re[3]: [Help-glpk] proposal for gnu lp/mip low-level format, Michael Hennebry, 2004/07/29
- Re[5]: [Help-glpk] proposal for gnu lp/mip low-level format, Andrew Makhorin, 2004/07/30
- Re[5]: [Help-glpk] proposal for gnu lp/mip low-level format, Michael Hennebry, 2004/07/30