Error using / Matrix dimensions must agree.

Hello everyone, can you please help me with this problem? I currently in my project's for Iterative Method. But I can't run the coding because of this problem.

Delamda = DelP/J;

Attached below is my full coding, can you guys help me?

clear
clc

a = [671 574 374 374 461 630 548 227 173 175 186 230 225 309 323];
b = [10.1 10.2 8.8 8.8 10.4 10.1 9.8 11.2 11.2 10.7 10.2 9.9 13.1 12.1 12.4];
c = [0.000299 0.000183 0.001126 0.001126 0.000205 0.000301 0.000364 0.000338 0.000807 0.001203 0.003586 0.005513 0.000371 0.001929 0.004446];
PD = 2630;
DelP = 10;

% define fuel cost quaratic equation
cost = [671 10.1000 0.000299 
    574 10.2000 0.000183
    374 8.8000 0.001126 
    374 8.8400 0.001126 
    461 10.4000 0.000205 
    630 10.1000 0.000301
    548 9.8000 0.000364
    227 11.2000 0.000338
    173 11.2000 0.000807
    175 10.7000 0.001203
    186 10.2000 0.003586
    230 9.9000 0.005513
    225 13.1000 0.000371
    309 12.1000 0.001929
    323 12.4000 0.004446];

% define Pi_min and Pi_max 
mwlimits = [150 455
150 455
20 130
20 130
150 470
135 460
135 465
60 300
25 162
25 160
20 80
20 80
25 85
15 55
15 55];
Pdt = 2630;

lamda = input('Enter estimated value of Lamda = ');

fprintf(' ')

disp ['Lamda P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 DP'...' grad Delamda'];

iter = 1;

while abs(DelP) >= 0.001 
iter = iter + 1;
P = (lamda - b)./(2*c); 
DelP = PD - sum(P);
J = sum(ones(length(a),1)./(2*c));
Delamda = DelP/J; 
disp [lamda,P(1),P(2),P(3),P(4),P(5),P(6),P(7),P(8),P(9),P(10),P(11),P(12),P(13),P(14),P(15)DelP,J,Delamda];
lamda = lamda + Delamda; 
end

totalcost = sum(a + b.*P + c.*P.^2);

[Rik]

Without an appropriate value as the initial estimated value of Lambda we can't run your code. Also, please chech if this is indeed the syntax you mean.

More importantly: what are you trying to do? Your code is devoid of any comment, so it is difficult to understand what you intend it to do.

[Muhammad Ezree Amree bin Amran]

my lambda = 8.35

After I enter the value of the lambda, it will appear totalcost at the workplace section. But I didn't get the output

[Hadi Jalali]

Hi friends. I want to need a code to solve ELD by third degree cost fuel. But I have no idea. Please help me Best wishes H. Jalali

[Rik]

@Hadi Jalali That sounds like a poorly phrased question unrelated to this one. Have a read here and here. It will greatly improve your chances of getting an answer.

Answer 1

[Rik]

If you make it an element-wise division, your code will run without errors. Since you still haven't really explained anything you're doing, I don't know if the result makes any sense.

Delamda = DelP./J;
%             ^ add that

Test on the full code:

lamda = 8.35;

a = [671 574 374 374 461 630 548 227 173 175 186 230 225 309 323];
b = [10.1 10.2 8.8 8.8 10.4 10.1 9.8 11.2 11.2 10.7 10.2 9.9 13.1 12.1 12.4];
c = [0.000299 0.000183 0.001126 0.001126 0.000205 0.000301 0.000364 0.000338 0.000807 0.001203 0.003586 0.005513 0.000371 0.001929 0.004446];
PD = 2630;
DelP = 10;
% define fuel cost quaratic equation
cost = [671 10.1000 0.000299 ; 574 10.2000 0.000183 ; 374 8.8000 0.001126 ; ...
    374 8.8400 0.001126  ; 461 10.4000 0.000205  ; 630 10.1000 0.000301 ; ...
    548 9.8000 0.000364 ; 227 11.2000 0.000338 ; 173 11.2000 0.000807 ; ...
    175 10.7000 0.001203 ; 186 10.2000 0.003586 ; 230 9.9000 0.005513 ; ...
    225 13.1000 0.000371 ; 309 12.1000 0.001929 ; 323 12.4000 0.004446];
% define Pi_min and Pi_max 
mwlimits = [150 455;150 455;20 130;20 130;150 470;...
    135 460;135 465;60 300;25 162;25 160;20 80;...
    20 80;25 85;15 55;15 55];
Pdt = 2630;

iter = 1;
while abs(DelP) >= 0.001 
    iter = iter + 1;
    P = (lamda - b)./(2*c); 
    DelP = PD - sum(P);
    J = sum(ones(length(a),1)./(2*c));
    Delamda = DelP./J; 
    lamda = lamda + Delamda; 
end

totalcost = sum(a + b.*P + c.*P.^2);
disp(totalcost)

   1.0925e+05

[Muhammad Ezree Amree bin Amran]

I need to analyze the economic dispatch solution using Newton Method. The data are the one in the bracket. The load demand is 2630 MW. And delamda is one of the formula that I've learnt.

Btw, the one you fixed is absolutely correct xD ! the answer is same like my calculation! Thank you so much.

[Rik]

You're welcome. If I solved your issue, please consider marking it as accepted answer.

Also some general advice: use functions and write comments. Every line (or at least few lines) should have a comment explaining the idea behind it (i.e. explain why), and your function should explain the syntax (input options), and the expected output.

%not this:

%multiply v and t
s=v*t;

%but this:

%calculate traversed path length
s=v*t;