Search found 38 matches

by Alexanre.ito
1 year ago
Forum: Syntax
Topic: Initial Value - Condition
Replies: 2
Views: 3496

Re: Initial Value - Condition

thank you very much.
bussieck wrote: 1 year ago Read up on conditional assignment in the following section: https://www.gams.com/latest/docs/UG_Con ... rOnTheLeft

Code: Select all

dr.L (n,np)$arc(n,np)     = 0.1;
-Michael
by Alexanre.ito
1 year ago
Forum: Syntax
Topic: Initial Value - Condition
Replies: 2
Views: 3496

Initial Value - Condition

Dear, I need to specify the initial value of a variable, but it should only apply to the conditions that are presented in the table. SET n / n1 * n20 / nn (n,n) alias(n,np) TABLE arc(n,n) (GRAPH - ARCS and NODES) n1 n2 n3 n4 n5 n6 n7 n8 n9 n10 n11 n12 n13 n14 n15 n16 n17 n18 n19 n20 n1 n2 1 n3 1 n4 ...
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Re: Negative exponential

Hi Steve, Thanks for your time. I have an equation (binary) that I use to select the direction flow, as you explained, using the example WATER and WATERX from GAMS Model Library. Probably my problem concerns the conditional flow equation. am, ir, rh and Q are variables and "mann" is a para...
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Re: Negative exponential

Atharv, thanks again

Now I see, I"ll try this condition.
I used the BigM to a another equation, I hadn't thought of using this one too.
And a small number together.

I'm glad for your attention
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Re: Negative exponential

Thanks Atharv, I'm understanding a little more about GAMS. first thank you very much for your patience, So, I have a condition that I need to test, if the transport occurs from the node (n) to the (np), or the opposite (np,n). One of this 2 situations will occurs. The other will be zero, or not occu...
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Re: Negative exponential

Yes, my Qi and Qf are positive variables. But in my problem I have to select the direction (binary variable) that if is 1 the Qi is the sum of the flow before of this pipe. So, some times Qi will be zero, if not ocorre the flow. 1) Should I add the binary variable in this equation? something like: E...
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Re: Negative exponential

uote=abhosekar post_id=29253 time=1637252514 user_id=1684] what you show in equations and what you are writing in GAMS are two very different equations. Which one is right? Based on what you wrote, your equation should be ir =g= 0.0055*Qi**(-0.47) ir =l= 4.65*Qf**(-0.67) not sure how that translates...
by Alexanre.ito
2 years ago
Forum: Syntax
Topic: Negative exponential
Replies: 11
Views: 6615

Negative exponential

Hi I have an equation as ir >= 0,0055* Qi^(-0,47) ir <= 4,65 * Qf^(-0,67) ir (m/m) and Q (L/s) are variable. I tried to declare into the GAMS as: Equation: Slope1.. ir**15 * (Qi)**7 =g= 0.0055**15 Slope2.. ir**3 * (Qf)**2 =l= 4.65**3 ; But returns an error: "All Jacobian elements in the row are...
by Alexanre.ito
2 years ago
Forum: Modeling
Topic: Disjunctive programming with Big M approach
Replies: 2
Views: 1916

Re: Disjunctive programming with Big M approach

Hi,
I'm not sure how it could be helpful

Try this, using
X - variable
D - Parameter or constantly
y - binary
M - BigM
i and j - the SET.

Code: Select all

X(j)-D(i) =l= M*(1-y(i,j));
by Alexanre.ito
3 years ago
Forum: Syntax
Topic: Cost from table
Replies: 1
Views: 2271

Cost from table

Hi I'm with a problem, I don't know how to declare an equation to calculate the cost. I have to find a diameter, this diameter have a cost exemple: SET d /d1*d7 /; nn /n1.n2, n1.n3, n3.n1, n3.n2/; PARAMETERS dc(d) diam. comercial (m) / d1 0.100 d2 0.150 d3 0.200 d4 0.250 d5 0.300 d6 0.350 d7 0.400 /...