How can I fix this error - "Error using / Matrix dimensions must agree"

I am trying to get values for y with T in the range 800 - 1100. the function I have called antoine works for single values but i get the error seen in the screen shot when i try to use the linspace command. Any idea how i can fix this?

[the cyclist]

For future reference, it is better to upload the code itself, rather than a screenshot of the code. That way, we can paste it into MATLAB directly.

[Anila Khan]

When i run this program it give me error. Error screen shoot attach here please guide me.

clc clear all close all m=30; n=30; snr=20; %Generation of corelation matrix

R=eye(m,m) R(m+1:m+1:end)=0.2; R(2:m+1:end)=0.2;

generations=100:100:500 no_ofDataRuns=500 for gen=1:length(generations) genError=0 for i=1:no_ofDataRuns B=randsrc(m,n) tx=randsrc(1,m) r=awgn(tx,snr) FF=Fit_PSO(r, B, R, m) for cyc=1:generations(gen) Pb=FF(:,2:end) %pb=B; Gb=FF(1,2:end) V=zeros(m,n) for k=1:m C=(Pb(k,:) - B(k,:)); D=(Gb - B(k,:)); V(k,:)=V(k,:) + rand().*C + rand().*D; %V(k,:)=V(k,:) + rand().*(Pb(k,:) - B(k,:)) + rand().*(Gb - B(k,:));

      end
      for a=1:m
          for b=1:n
              S(a,b)=1/(1+exp(-V(a,b)))
              if S(a,b)>rand()
                  B(a,b)=1
              else
                  B(a,b)=-1
              end
          end
      end
      updated_fitness=Fit_PSO(r,B,R,m)
      updated_fitness_error=updated_fitness(1,2:end)

      Error(cyc)=pdist([updated_fitness_error;tx],'hamming')
end
      genError=(genError+Error(cyc))
    end
      BER(gen)=genError/[generations(gen)*no_ofDataRuns]

end semilogy(generations,smooth(BER),'Color',[0 0 1]) xlabel('Number of cycles'); ylabel('Bit Error Rate'); txt = strcat('BER Vs generations with ',int2str(snr),'db AWGN') title('BER Vs NOC') grid on; hold on;

Answer 1

[Guillaume]

Learn the different between arrays (eg ./) and matrix (eg /) operators.

Replace the two / by ./, and ^2 by .^2

And if you want to avoid potential nasty surprises in future code, never write a subtraction as

 a -b

either put a space on both sides of the operator

a - b

or on neither:

a-b

Compare the result of

[2 - 1]
[2-1]
[2 -1]

to see why your notation is problematic.

[Diah Junaidi]

How about this sir?? Would you please check mine too. I dont know what going to do sir :(

[Ivan Dwi Putra]

function dx = trainfinalmodel(t,x)

%Parameter Massa

m1 = 65; % massa train set 1 dalam kg

m2 = 65; % massa train set 2 dalam kg

g = 10;

%Parameter Gaya

f1 = 117; % dalam N

f2 = 117; % dalam N

c_0_1 = 0.0016*m1*g;

c_1_1 = 0.00008*m1*g;

c_2_1 = 0.0000006*m1*g*(x(2)^2) ;

c_0_2 = 0.0016*m2*g;

c_1_2 = 0.00008*m2*g;

c_2_2 = 0.0000006*m2*g*(x(4)^2) ;

v_0 = 60;

hstar = 120;

a_1 = -1/m1*(c_1_1+2*c_2_1*v_0);

a_2 = -1/m2*(c_1_2+2*c_2_2*v_0);

a_1_head = 1-(a_1*hstar);

a_2_head = 1-(a_2*hstar);

b = 1;

p_1 = -1/m1*(c_0_1 - c_2_1*(v_0)^2);

p_2 = -1/m2*(c_0_2 - c_2_2*(v_0)^2);

x = [x(1);x(2);x(3);x(4)];

x_transpost_t = transpose(x);

A = [0 a_1_head 0 0;

0 0 0 0;

0 (a_2_head-1) 0 a_2_head;

0 0 0 0;

];

B = [-b*hstar 0;

b 0;

0 -b*hstar;

-b -b;

];

U_t = [f1;f2];

W = [((a_1 - 1)*v_0) - p_1*hstar;

((a_2 - 1)*v_0) - p_2*hstar;

];

dx = (A.*x_transpost_t) + (B.*U_t) + W;

end

please check my mine too, i have same problem the matrix dimension must agree

[Anand Kumar]

well approach.

Answer 2

[the cyclist]

You need to use element-wise division, not matrix division.

Use "./" in place of "/"

See this documentation for an explanation of the difference.

You are similarly going to want ".^" rather than just "^" for raising to a power.

[Diah Junaidi]

How about this sir?? I dont know what should i do :( would you please check mine sir ? :(

[the cyclist]

Rather than putting a comment a question that is nearly a year old, I suggest that you create a new question. Attach your code (as you did here), tell us the full text of any error messages you are getting, and ask specific questions.