Re: Constraint definition is not valid: WHY?

*To*: mathgroup at smc.vnet.net*Subject*: [mg131380] Re: Constraint definition is not valid: WHY?*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Tue, 2 Jul 2013 00:47:22 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net*References*: <20130701094838.8194B6A23@smc.vnet.net>

You wrote ReplaceAll incorrectly. v1 = express ./ Par should be written v1 = express /. Par Perhaps this is just a typo in your e-mail 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 at 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=V1-V2; > > 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 > >

**References**:**Constraint definition is not valid: WHY?***From:*aless.bolli@gmail.com