[Bug-glpk] Re: Only MPS writer warns about empty columns and other writers don't

[Andrew Makhorin]

> This is a minor inconsistency.
> 
> I tried to write out my problem to various formats. And only MPS writer 
> printed this:
> Warning: problem has 27 empty column(s)
> 
> Other writers: MIP,SOL,LPX didn't complain even though this is the same 
> problem.
> 
> Different writers should produce the same warning on the same problem.
> 

No, they shouldn't. The reason is that the mps format, unlike other
formats, is column-oriented, so an empty column cannot be written in an
mps file without introducing a dummy zero coefficient in some row.