Calculating infinity norm in ampl

[Juan Pablo Fernández G]

Hi, I am new user in ampl, i would like to know how can i calculate the infinity norm in ampl?

infinity norm is the maximum of absolute value of a member of vector (simply array.)

thanks for your collaboration.

[Robert Fourer]

If you have

set S;
param a {S};

then the infinity norm of a (considered as a vector) is

max {i in S} abs(a[i])

If you want to use the infinity norm of a vector of variables in your model, however, then you need to convert it to a formulation that uses linear expressions that solvers can handle. The formulation depends on how the inifinity norm expression appears in the model, however -- there is not a single answer that applies to all cases.

Bob Fourer
am...@googlegroups.com

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