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Re: Constraint definition is not valid: WHY?
Posted:
Jul 2, 2013 12:33 AM


You wrote ReplaceAll incorrectly.
v1 = express ./ Par should be written v1 = express /. Par
Perhaps this is just a typo in your email and not how you wrote your code since this would give an error.
Functions use square brackets; for example,
V1 = f(e1, x) should be written V1 = f[e1, x]
In the statement
NMaximize[{objopt > 0, constr == 0}, {e1, e2, x}, Method > NelderMead]
there is no expression to be maximized, just two constraints: an inequality and an equation.
The error message indicates a problem with the constraint "expression" but you have not
defined expression in the code snippets shown.
Bob Hanlon
On Mon, Jul 1, 2013 at 5:48 AM, <aless.bolli@gmail.com> wrote:
> I am tring to use Nmaximize in Mathematica This is How I proceeded: > > 1) define a list of parameters: Par = {a>1, b>3, etc}; > > 2) define two functions: f1: v1=express./Par f2: v2=express./Par > > After this the expression are numerical except for the variables: > > V1=f(e1,x) and V2=f(e2,x) > The objective function to be maximized is V1/(e1+e2) I defined the > constraint as constr=V1V2; > > then I used the Nmaximize: > > NMaximize[{objopt > 0, constr == 0}, {e1, e2, x}, Method > NelderMead] > I obtained the following error: > > NMaximize::bcons: "The following constraints are not valid: "expression". > Constraints should be equalities, inequalities, or domain specifications > involving the variables" > > I checked that only those variables are present in the constraint and > objective function (other are numerical parameters) I do not understand why > this error appears can someone help me? > > Thank you > > Alex > >



