I want to write exponential function in AMPL

[Sachin Argade]

Hello,

I want to write exponential function. For example suppose I have to
write e^([15000/383-15000/(H-273)]) in AMPL, Can I write like this
subject to constr2{i in 1..24}:TLAF[i]>=e^((15000/383)-(15000/
((detlathetaor[i])?
Is e^(......) is the right syntax or right way to write exponential ?
Please let me know,

Thanks,
Sachin.

[Robert Fourer]

The exponential function in AMPL is exp(...), where ... is replaced by any
expression that evaluates to a number.

You can write e^(...), but only if you define a parameter e and set it to
exp(1). The exp function is very slightly more accurate, however.

Bob Fourer
4...@ampl.com

[Sachin Argade]

oh ok thanks Bob.

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Sachin Argade

[rim...@gmail.com]

Hi,

I have a problem in defining an Exponential parameter,

here is the problem,

param Emrg {r in 1..R} Exponential ()

I do not know how can I define this parameter in a way that it follows a exponential function with Lamda=8?

How should I write this parameter Emrg in .dat form?

Any help would be highly appreciated!

Amir

[victor.z...@gmail.com]

The function you are looking for is called exp. Please see here for the list of built-in AMPL functions.

HTH,

Victor

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[rim...@gmail.com]

Can you please give an example how to define a parameter that follows exponential distribution in .mod and then how can I assign value to the mean of exp function in .dat file.

Thank you!

[Robert Fourer]

You can write

param emean > 0;
param a = exp(emean);

Then you can assign a value to param emean in the data file. Note however that the "param a = ..." statement will only assign a random sample from the exponential distribution (with mean of emean) to the parameter a. Currently it is not possible to define a "random" parameter that has an exponential distribution but no particular value.

Bob Fourer
am...@googlegroups.com

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From: am...@googlegroups.com [mailto:am...@googlegroups.com] On Behalf Of rim...@gmail.com
Sent: Monday, September 14, 2015 12:27 PM
To: AMPL Modeling Language
Cc: sachin...@gmail.com