Lindo error in stochastic programming

GAMS
1

Hi experts,

I am new to stochastic programming and GAMS.

While executing the GAMS file for stochastic programming I got following errors through emp file.

**** SOLVER STATUS FILE LISTED BELOW
=C*** emp.info line 3: Cannot find random parameter “=” in model.
=C Hint: EMP keys like Chance, Stage, VaR, … are not allowed as symbol name
s
=C*** Error processing empinfo file
=C*** Problem in getObjects
=C*** Failure calling solver: LINDO (rc=1)
**** SOLVER STATUS FILE LISTED ABOVE
I could not find any solution to the problem. Please help.

Attaching the source GAMS file.
Thanks.
Untitled_10.gms (2.27 KB)

2

Hi,

I found a few (formatting) problems in your emp.info file:

  • You missed a line break before the last line
  • traffic_sc does not exist in the model, you should not mention it as stage 2 symbol
  • You did not name the random variables in the loop, but put in some numbers instead

According to these problems, I did some small adjustments in the EMP Annotations part, which allowed to solve the model:

* EMP Annotations
File emp / '%emp.info%' /; put emp '* problem %gams.i%'/;
*emp.nd=2;
loop(tra, put 'randvar' traffic_bw.tn(tra) 'poisson' 10 /)
$onput
stage 2  traffic_bw phi sc_availability1 sc_availability2
$offput
putclose emp;

I hope that helps,
Lutz

3

Thanks a lot… :smiley: :smiley: