NMinimize ignores constraints and crashes

*To*: mathgroup at smc.vnet.net*Subject*: [mg61269] NMinimize ignores constraints and crashes*From*: "janusonis" <skirmantas.janusonis at nospam.yale.edu>*Date*: Fri, 14 Oct 2005 05:54:17 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I saw somebody's similar message posted last year, but it went unanswered, so I still need a solution. Why NMinimize ignores my constraints, gets into a region where my function yields complex values, and then stops? I explicitly tell the procedure not to go outside the constraints, but it still does it. A simple example: NMinimize[{Sqrt[x - y], x ≥ y &&x y ≥ 9}, {{x, 4., 5.}, {y, 3., 4.}}] NMinimize::nrnum: The function value 0.0819328+0.535013I is not a real number at {x, y} = {3.27193, 3.55817}. There are obviously infinitely many minima, at which the value of the function is 0. What is important here, though, is that NMinimize again ignores x>=y, gets complex values and chokes.

**Follow-Ups**:**Re: NMinimize ignores constraints and crashes***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>