[Help-glpk] reporting bugs / problems with GLPK 4.8

[Björn]

Hi, everybody!

I am using GLPK 4.8 with MSVC++ 6.0 (WinXP). In this mail I would like to 
report some bugs I encountered. If somebody knows how to circumvent those 
problems, thanks a lot for letting me know.


1) Screen messages cannot be switched off

According to the GLPK 4.8 reference manual (p. 54), setting the parameter 
LPX_K_MSGLEV to 0 entails that solver routines generate no output. After 
setting this parameter to 0, I made the following experiences:

a)
 - The LP solver lpx_simplex(lp) functions correctly (does not display 
anything).
 - The MIP solver lpx_integer(lp) prints the final result, but no prior 
iterations.
 - The Interior Point solver lpx_interior(lp) gives exactly the same output 
as when LPX_K_MSGLEV is set to 3 (full output).

b)  I wrote the following code which reads data from a CPLEX LP file and 
should not display anything on the screen.

lp = lpx_create_prob();
lpx_set_int_parm(lp, LPX_K_MSGLEV, 0); // ought to switch out messages
lp = lpx_read_cpxlp("plan.lp");

Unfortunately, the third line sets LPX_K_MSGLEV back to 3 (full output) and 
prints some information on the screen. It thus overrides the second line. 
The first line is necessary because the program crashes when using the 
second line without the first line.

Does anybody know how to fix LPX_K_MSGLEV to 0? Is there another way to 
temporarily suppress output in C++?


2) Bug in the function lpx_write_cpxlp(lp, "results")

I read data from a CPLEX file with "Integer bin2 bin3 bin4 bin5" and other 
continuous variables (also understood by the C++ program and subsequent 
solution routines).
Writing a CPLEX file from that same data of the lp structure results in 
"Generals bin2 bin3 bin4 bin5" (+ other variables continuous by default) 
which represents continuous variables and not integer ones. Moreover, 
continuous variables should be called "General" and not "Generals" according 
to the GLPK 4.8 reference manual.


I hope this can help, and thanks for any comments.

Best regards,
Bjoern 



        

        
                
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