Hiiii having problem in coding optimazation function

hiii i have problem in defining objective function for optimization. my objective function is

y=sum(abs(Voc-Vbc));
where Voc is given data and Vbc is obtained by 

Vbc=(((Q./C1)+(Ic*R2)).*exp(-tc./(R2.*C1)))+Vo-(Ic*(R1+R2));
in this Q tc and Ic are constant and R1 C1 R2 and Vo is obtained from

R1 = ((a(1)+a(2)*cr+a(3)*(cr^2))*exp(-a(4).*SOC))+(a(5)+a(6)*cr+a(7)*(cr^2));
R2 = ((a(8)+a(9)*cr+a(10)*(cr^2))*exp(-a(11).*SOC))+(a(12)+a(13)*cr+a(14)*(cr^2));
C1 = (-(a(15)+a(16)*cr+a(17)*(cr^2))*exp(-a(18).*SOC))+(a(19)+a(20)*cr+a(21)*(cr^2));
Vo = ((a(22)+a(23)*cr+a(24)*(cr^2))*exp(-a(25).*SOC))+(a(26)+a(27).*SOC+a(28).*(SOC.^2)+a(29).*(SOC.^3))-(a(30)*cr)+(a(31)*(cr^2));
Here SOC is an array and cr is constant a is array with (1, 31) dim . this a matrix is variable for our optimization.
in my program i want R1 C1 R2 and Vo always remain positive. how i can define it in matlab so this values always remain positive.

[Alan Weiss]

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Alan Weiss

MATLAB mathematical toolbox documentation

[venu sangwan]

i have updated it plz help

Answer 1

[Alan Weiss]

It is very hard to understand you, so my comments might be off base. I am not sure that I understand what your control variables are. Control variables are the ones that you change to try to optimize something.

Suppose that your control variables are R1, C1, R2, and V0. Then you write your objective function for the lsqnonlin function as

 function y = myfun(x,Vbc)
 R1 = x(1);
 C1 = x(2);
 R2 = x(3);
 V0 = x(4)
 % Now write the calculation of Voc
 % End the calculation with
 y = Voc - Vbc

and pass your function as

 fun = @(x)myfun(x,Vbc); % gets the objective function
 solution = lsqnonlin(fun,x0) % you need an initial guess x0

I hope this helps,

Alan Weiss

MATLAB mathematical toolbox documentation

[venu sangwan]

variable are a(1,31) matrix from which R1, C1, R2, and V0 are formed . then they are use to form Vbc which is use in objective function