[AMPL 25038] Which is more computationally efficient??

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1

Dear all,
I have a question:
Which is more computationally efficient:
using computed variables
or
including the equivalent constraint in the formulation?

var A: B+C
vs
subject to A==B+C

Thank you!!
R

2

Usually it is preferred to write

var A = B + C;

because then the expression “B + C” is substituted for A; the solver does not see the variable A or the constraint “A = B + C”. However, there can be exceptions where the number of “defined variables” like A is very large. So if you are finding that AMPL is taking an especially long time to generate the problem, you may want to try the alternative,

var A;
subject to Adefn: A = B + C;

to see whether it is faster.

3

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4

Thanks !!

El El mié, 1 may 2024 a las 14:50, AMPL Google Group via AMPL Discourse <notifications@ampl.discoursemail.com> escribió: