sign problem in defined constraint

GAMS
1

Hi Gams family,

I am currently using GAMS to code a mathematical model. I have a problem on how GAMS interpret my constraints.

In the attached file there is an equation with the name of cg_2_1(i,j,p). After running the code, I wanted to be sure whether GAMS created the correct equations or not and I traced the .lst file. except this one, all equations were correct. This equation included '+'s (plus) instead of '-'s (minus).

I did not find where I am making mistake.

Please help me. This is about my master thesis. Thank you in advance.

Samet

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SDTSP_tdkrx5a_input_3xct_1.gms (2.39 KB)

2

What does “(0)” mean in an entry in a .lst file? An example is given below.

cg_2_0(node1,node2,position1)… d(node1,node2,position1)

  • (0)*x(node1,position1) + (0)*x(node2,position1) + (0)*x(node3,position1)

  • (0)*w(node1,node2,position1) =G= 0 ; (LHS = 0)


    2013/11/9 Samet Tonyalı

Hi Gams family,

I am currently using GAMS to code a mathematical model. I have a problem on how GAMS interpret my constraints.

In the attached file there is an equation with the name of cg_2_1(i,j,p). After running the code, I wanted to be sure whether GAMS created the correct equations or not and I traced the .lst file. except this one, all equations were correct. This equation included '+'s (plus) instead of '-'s (minus).

I did not find where I am making mistake.

Please help me. This is about my master thesis. Thank you in advance.

Samet

\

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3

Hi Samet



The zero is just the value of the multiplication factor of the parameters in your equation, e.g. in this case w(i,j,p)*val(k)*g(t,k)*ct(l,t). It looks like the multiplication factor is zero…



Gams writes the linearization of your equations in the equations listing and presumably treats the zero as +Zero and not –zero. If the value of the multiplication coefficient is negative, you will see the proper signs.



Cheers


Renger





From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of Samet Tonyali
Sent: Samstag, 9. November 2013 18:06
To: gamsworld@googlegroups.com
Subject: Re: sign problem in defined constraint



What does “(0)” mean in an entry in a .lst file? An example is given below.



cg_2_0(node1,node2,position1)… d(node1,node2,position1)


\

  • (0)*x(node1,position1) + (0)*x(node2,position1) + (0)*x(node3,position1)


    \
  • (0)*w(node1,node2,position1) =G= 0 ; (LHS = 0)



    2013/11/9 Samet Tonyalı

Hi Gams family,



I am currently using GAMS to code a mathematical model. I have a problem on how GAMS interpret my constraints.



In the attached file there is an equation with the name of cg_2_1(i,j,p). After running the code, I wanted to be sure whether GAMS created the correct equations or not and I traced the .lst file. except this one, all equations were correct. This equation included '+'s (plus) instead of '-'s (minus).



I did not find where I am making mistake.



Please help me. This is about my master thesis. Thank you in advance.



Samet


\

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–
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