GAMS World Forum

Hi, I'm using the SBB solver as MINLP. in my model have some equations that the variables are very small, between [0.001 , 0.1]. So I use ".scale". But some equations still have this problem. Some equations have power lower than 1 (ex. var**0.47), so I change the equation to ( var1 **100 =...

Thanks!! that's right!! I understood and it is perfect! But Where should I declare this?? In Equation?? Like Equation eq1(n,nd) equation 1 eq2(n,nd) equation 2 ...; eq1(n,nd).. dr(n,nd)$(dcal(n,nd) gt 150 and dcal(n,nd) le 200.01) = 200; eq2(n,nd).. dr(n,nd)$(dcal(n,nd) gt 200 and dcal(n,nd) le 250....

My problem with the syntax in GAMS is how can I limit the result to being specific values, like for example: the result of the diameter should be 150mm, or 200mm or 250mm or 300mm or 350mm or 400 or 500. In my case the diameter is a variable, so reading the McCarl GAMS User guide I found two ways to...

Renger wrote: ↑4 years ago Hi
This might be resolved by setting a starting value that is not equal to zero. If you don't set a starting value for your variables, Gams assumes zero.
You could for example set THETA.L = 1;
Cheers
Renger

Yes! this help with this problems.
Thanks

GAMS supports trigonometric functions. What are the functions you have problems with? Extrinsic functions are to implements your own functions. Best My problems is with this equation: * Diameter for each tube with flow dred(a).. dr(a) =e= vcPower((abc1(a)*man*qr(a)/sqrt(ir(a))),(3/8)); eq1(a).. abc...

Hi, I was studding in how to implement trigonometric functions. I founded this site, about Extrinsic Functions. https://www.gams.com/latest/docs/UG_ExtrinsicFunctions.html#UG_ExtrinsicFunctions_BuildYourOwn-TrigonometricLibraryExample I need to use the angle with radian unit. So at GAMS website they...

Yes, you're right I need to improve!! I need this lower bound, during the calculation. But the diameter need to be Zero, when is not allowed a tube, in other words, when flow is Zero, the diameter is zero too. Hi, You set a lower bound of 0.15 for d(n1 .n5): d.lo(n,np)$a(n,np) = dmin; Hence, it cann...

I'm developing a simple problem of water transport. But I need a help, someone please could help me. In my code the flow conservation equation at each node, is working. (I'm using waterx.gms as reference). But I need a code that exclude tubes which have zero flow. I tried to multiply by the binary h...

Using this expretion
Q(m,n) and Q(am-1,n)

GAMS will use the same matrix of data, in this case, will use the same matriz of the flow data?

Hi, I'm trying to write a code to calculate the flow of a snippet. The section should receive the flow of the previous sections. But my problem is the matrix "q(n,np)" depends on itself. Apresentação1.jpg Set n nodes / n1 * n48 / a(n,n) arcos / n1.(n2,n9), n2.(n1,n3), n3.(n2,n4), n4.(n3,n5...