# MATLAB Syntex Problem for optimization

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Rasel Ahmed on 17 Sep 2020
Answered: Ayush Gupta on 8 Oct 2020
Hi Everyone,
I am working on LNG plant optimization and using Matlab and Hysys as optimization and process simulation software and I have interfaced them using a spreadsheet.
Now, Hysys calculates values of variables x1, x2, x3, x4 and send to MATLAB, which optimizes them and send back the values to Hysys.
The sum of these four variables should be equal to one, that is x1+x2+x3+x4=1, that is if value of x1 is reduced by MATLAB then the values of remaining variables should be increased to make the sum equals 1.
I am not figuring out a way to correctly write in MATLAB. How should I formulate it?
Thanks.
##### 2 CommentsShowHide 1 older comment
Rasel Ahmed on 18 Sep 2020
Thank you sir John for your comment. Yes, I have GA, PSO codes and also have matlab toolbox. I tried to build the constraint in many ways but I can't find a way to properly state the constraint in Matlab.

Ayush Gupta on 8 Oct 2020
The MATLAB’s optimization toolbox can be used to solve this problem. We can define a problem using optimproblem function in MATLAB. Then we can declare optimal variables that will be used in the problem with optimvar function. After that we define the objective that is the variable that we want to optimize and constraints it has like we have the constraint of sum to be 1. To refer how to solve a problem, look at the Problem-Based Optimization Workflow here.