Nested if-then-else statement or multiple if-statements

[louisperrault]

Hello,

I have been solving a problem with AMPL (Knitro solver) where I create other variables based on the choice variables with If-then-else statements, for example (a few other variables are omitted for brevity):

var c1{i in N}= if (I[i]>=CutOff[i]) then ((Per1NetInc[i]/PweightC)+(Need/2)) else (omega1*(TotNetInc[i]/PweightC)+(Need/2)) ;

Here I[i] and another variable in CutOff[i] are the true choice variables. This has been working so far. Now, I am facing a situation where I have two cutoff values, this means that I would need something like the "elif" in Python or the nested if...else in R (https://www.programiz.com/r-programming/if-else-statement). 

Is a nested if-else statement possible in AMPL?

For example, could I write

var c1{i in N}= if (I[i]>CutOff1[i]) then (X1) else ( if (I[i]<CutOff2[i]) then (X2) else (X3) )?

Thank you so much for your time.

Regards,

Louis Perrault

[Robert Fourer]

An if-then-else is a kind of expression in AMPL. It can appear anywhere that an expression is valid, such as after the "else" of another if-then-else expression -- as in your example.

Bob Fourer
am...@googlegroups.com

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