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Re: [Fwd: Exportation/importation problem that seems to be related to de

From: Heinrich Schuchardt
Subject: Re: [Fwd: Exportation/importation problem that seems to be related to decimal numbers]
Date: Fri, 7 Aug 2020 08:32:09 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0

Dear Sylvain,

this is a known issue, cf.

http://glpk-java.sourceforge.net/usage.html#Locales describes that you
can call method GLPK.glp_java_set_numeric_locale("C"); to set the locale
for numbers to match the expectations of GLPK.

Please, inform me if this solves your problem.

Best regards


On 8/6/20 11:41 PM, Andrew Makhorin wrote:
> -------- Forwarded Message --------
> *Date*: Thu, 6 Aug 2020 17:12:26 -0300
> *Subject*: Exportation/importation problem that seems to be related to
> decimal numbers
> *To*: bug-glpk@gnu.org <mailto:bug-glpk@gnu.org>
> *From*: Sylvain Fournier <sylvain@wplex.com.br
> <mailto:Sylvain%20Fournier%20%3csylvain@wplex.com.br%3e>>
>> Hi,
>> I'd like to be able to export a model into a (text) file in order to
>> be able to run it again later. I noticed there are three couples of
>> procedures for this:
>>   * glp_write_lp / glp_read_lp
>>   * glp_write_prob / glp_read_prob
>>   * glp_write_mps / glp_read_mps
>> I tried with each of them, and failed to import the model for specific
>> reasons:
>>   * glp_*_lp: the exported file shows decimal numbers using a comma
>>     instead of a dot (it must be because it is the way to write
>>     decimals in Brazil). As a result, when trying to import back, I
>>     get the following message: "(line) *4: constraints section
>>     missing*". Note that if I manually replace the comma by a dot, I
>>     get another error: "*4: numeric constant '93.2807074368' out of
>>     range*".
>>   * glp_*_prob: when trying to import the file back, the program stops
>>     at the first line describing the objective coefficients (starting
>>     with 'a') with the following message: "*error: objective
>>     coefficient missing or invalid*". If I replace the ',' by a dot, I
>>     get the same message.
>>   * glp_*_mps: here it is even more strange. It seems that the
>>     exported file describes a cost function very different from the
>>     original model one (coincidentally - or not -, the only decimal
>>     numbers in this model are the variables cost coefficients). In
>>     fact, it looks like it mistook one of the constraints with the
>>     cost coefficients. I could send the original (lp) file and the
>>     generated (mps) file for a better understanding of the issue, if
>>     needed. Besides, the generated file doesn't export the rows and
>>     columns names, but instead uses names like C0000143 or R0000143,
>>     which makes the model far more difficult to understand.
>> Note that I am running GLPK through the Java wrapper libglpk-java-1.12.0.
>> Am I doing something wrong? Is there some workaround to this issue?
>> *Sylvain Fournier*
>> Operations Research Manager
>> *48 3239-2428*
>> WPLEX Software Ltda.
>> Rod SC 401 no. 8600 Corporate Park bloco 5 sala 101
>> 88050-000 Santo Antônio de Lisboa, Florianópolis SC +55 48 3239-2400
>> wplex.com.br <http://wplex.com.br/>

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