Hello guys, please help me to solve the below mentioned prograame. it is not running

D1=2;
D2=3;
D3=5;
Q1=4;
Q2=5;
Q3=6;
V1=4*Q1/(3.14*D1^2);
V2=4*Q2/(3.14*D2^2);
V3=4*Q3/(3.14*D3^2);
P1=5*D1^2;
P2=5*D2^2;
P3=0.5*D3^2;
if Vi<=10
   Cpv=0;
else
   for i=1:3
       Cpv=(1/15)*(Vi^2-100);
   end
end
%%%%
if Pj>=18
   Cpp=0;
else
   for j=1:3
       Cpp=Cpp+18-Pj;
   end
end

 Comment on this Answer

[Birdman]

What do you want this code to do?

[adarsh]

i want to get the value of: f=Cpv+CPP

Answer 1

[Image Analyst]

You need to define Vi and Pj. For example:

Vi = 5
Pj = 22

or whatever. If you do that, it runs.

[adarsh]

But here i is varying from 1:3 and similarly j is also varying from 1:3 and same v1, v2,v3 and p1,p2 and p3 are already defined. like V1=4*Q1/(3.14*D1^2);and P1=5*D1^2;

[adarsh]

i want the following to happen: if V1,V2 and v3 are less than 10, then Cpv=0 else CPV is to be obtained from the equation Cpv=(1/15)*(Vi^2-100); Similarly for CPP also

[Image Analyst]

You're not showing any loop where you're varying i and j, so no, you're NOT varying i from 1 to 3 and j from 1 to 3. You'd need a loop for that and you don't have one.

Also, did you mean V(i) and P(j) rather than Vi and Pj?

[Walter Roberson]

Do not expect Vi to know that i should be evaluated to determine which of V1, V2, V3, etc. that you want to access. Programming that way is Not Recommended.

http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[adarsh]

i am sending the file in the attachment. I want to minimize the function f using Genetic Algorithm

[Walter Roberson]

Your objective function is going to receive a vector of values in a single variable. Extract portions of that vector into variables inside the function. Use vectors and index them as needed.

[adarsh]

kindly send a small example

Answer 2

[Walter Roberson]

function cost = obj(x)
  P = x(1:10) ;
  V = x(11:18);
  cost = sum((P-7).^2) + sum((V-100).^2) ;

[adarsh]

% Since i have 22 variables will it go this way

function cost=obj(x) D=x(1:5); P=x(6:10); Q=x(11:16); V=x(17:22) L1=2; L2=3; L3=4; L4=5; L5=6; Q=20;Q4=5; Q1=3.14*D1^2*V1; Q2=3.14*D2^2*V2; Q3=3.14*D3^2*V3; Q5=3.14*D5^2*V5; Q6=3.14*D6^2*V6; Equality Constraints are: g(1)= Q1-Q2-Q3; g(2)= Q3-Q4-Q5; g(3)= Q2+Q5-Q6; g(4)=P1-P2-11.7*(L1*Q1/D1^5); g(5)=P2-P3-11.7*(L2*Q2/D2^5); g(6)=P2-P4-11.7*(L3*Q3/D3^5); g(7)=P4-P3-11.7*(L4*Q5/D4^5); g(8)=P3-P5-11.7*(L5*Q6/D5^5);

But then how to write the equations under penalty section in MATLAB

[Walter Roberson]

No, you would not use both the vector P and the separate variables P1, P2 and so on. You would index P with the appropriate offset.

[adarsh]

any example like i have g(5)=P2-P3-11.7*(L2*Q2/D2^5); so how to write for this

[Walter Roberson]

Replace each letter followed by a number, with the letter then () around the number. For example P(2)-P(3) and L(2)*Q(2)/D(2)^5

[adarsh]

is now the way correct. I have put indices on each letter. How to write and correlate the summation and if- else statement in the program.

[Jan]

@adarsh: Do not let the expression "Q1,Q2,Q3, ..." confuse you. Later in the document Q is an array and an index is used: Q(1), Q(2), ... Using vectors is the right way to go.