Re: [Bug-glpk] glpsol cannot solve exported CPLEX file

[Andrew Makhorin]

Hi Heinrich,

Thank you for your bug report.

> given the following model:
> 
> var x, >=0;
> minimize obj : x + 5;
> end;
> 
> I export it with
> 
> glpsol -m test.mod --wlp test.lp --check
> 
> I get
> 
> \* Problem: test *\
> 
> Minimize
>   obj: + x
> \* constant term = 5 *\
> 
> Subject To
> 
> End
> 
> 
> Then I run
> 
> glpsol --lp test.lp
> 
> and receive the following output:
> 
> Reading problem data from 'test.lp'...
> test.lp:9: missing variable name
> CPLEX LP file processing error
> 
> 
> The bug is in glpcpx.c. In parse_constraints() the token check should be 
> moved from the end of the loop to the start of the loop.

I don't know how to better fix this bug. The problem is that your lp has
no constraints, however cplex lp format requires 'Subject To' section to
be non-empty.