Originally posted by: Jutto

Hello

Using CP, is it possible to include trigonometric functions for defining variable expressions.
For instance:

dexpr float deltaYs2 in Segments = ((lines2*cos(angles2)));

I currently don't understand how such mathematical expressions can be used.

Thanks for the help, Martin
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: ol

Hello,
a float expression can be used in an objective function, in another expression, or in a constraint. For instance, you can see the example floatexpr.mod:

using CP;

dvar int i in 1..100;
dvar int j in 1..100;
dvar int k in 1..99;

dexpr float kf = k/100;
dexpr float arhttp://i in 1..10 = k/i;

minimize kf + sum(i in 1..10)ar[i];

subject to {
i*(1+kf) == j;
}

However, trigonometric functions are not available in OPL, and you need to use the C++ API.

Regard,
Olivier
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: Jutto

Thanks for your help, Oliver

This is what I do not yet understand; what do I need to do to implement the C++ API into my OPL script and integrate a trigonometric function into an expression?

Best Regards, Martin
#ConstraintProgramming-General
#DecisionOptimization

Hi,

what you can do also is to compute the trigonometric values in execute blocks and then use those values in the subject to part.

int Nc=100; 

float pi=3.14; range r=0..Nc; 

float cosValueForI[r]; execute 
{ 

for(var i in r) cosValueForI[i]=Math.cos(i*2*pi/Nc); 
}

And then you can use cosValueForI in your constraints.

Regards
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: Jutto

Thanks a lot, Alex

I will try that out right away.

Best regards, Martin
#ConstraintProgramming-General
#DecisionOptimization