??? In an assignment A(I) = B, the number of elements in B and I must be the same.

Question

baby 2012-5-11

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采纳的回答： Image Analyst

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hello,,

i need help becoz something's wrong with my code,,

please help me,,

that error show that -->>

???  In an assignment  A(I) = B, the number of elements in B and I must be the same. 
Error in ==> w1(i)=w1(i)+dw1(i);

please help me,,

this is my homework and i must collect it tomorrow,,

my Code

p1=[0 1 0 2];
p2=[0 1 0 2];
t=[1 1 1 0];
%Weight
w1=0;
w2=0;
b=1;
teta=0;
w1new=1;
%Iteration
for j=1:3
for i=1:5
%Calculate n 
      n(i)=w1*p1(i)+w2*p2(i)+b;
%Calculate Output
   if n(i)>teta
     a(i)=1;
   else 
     a(i)=0;
end
   %calculate error value
   error(i)= t(i) - a(i);
   dw1(i)=error(i)*p1(i);
   dw2(i)=error(i)*p2(i);
   db{i}=error(i);
   w1(i)=w1(i)+dw1(i);
   w2(i)=w2(i)+dw2(i);
   b(i)=b(i)+db{i};
end
end
disp(['P1 : ',num2str(p1)]);

i dont know what's wrong with my code,,,

please help me :(

4 个评论
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Daniel Shub 2012-5-11

Over writing MATLAB functions with variables (e.g., i, j, error, and db) is bad style and can lead to all sort of problems.

Greg Heath 2012-7-15

Why are you using loops when your result can be obtained by matrix operations?

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Answer 1

Image Analyst 2012-5-11

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https://ww2.mathworks.cn/matlabcentral/answers/38107-in-an-assignment-a-i-b-the-number-of-elements-in-b-and-i-must-be-the-same#answer_47534

在 MATLAB Online 中打开

I have no idea what this does, or if my "fix" below is what you want, but at least it runs. You didn't initialize p1 and p2 to have the required 5 elements, and you didn't use w1 and w2 as matrices everywhere.

p1=[0 1 0 2 0];
p2=[0 1 0 2 0];
t=[1 1 1 0 0];
%Weight
w1 = zeros(1,5);
w2= zeros(1,5);
b= ones(1, 5);
teta=0;
w1new=1;
%Iteration
for j=1:3
  for i=1:5
    %Calculate n
    n(i)=w1(i)*p1(i)+w2(i)*p2(i)+b(i);
    %Calculate Output
    if n(i)>teta
      a(i)=1;
    else
      a(i)=0;
    end
    %calculate error value
    error(i)= t(i) - a(i);
    dw1(i)=error(i)*p1(i);
    dw2(i)=error(i)*p2(i);
    db{i}=error(i);
    w1(i)=w1(i)+dw1(i);
    w2(i)=w2(i)+dw2(i);
    b(i)=b(i)+db{i};
  end
end
disp(['P1 : ',num2str(p1)]);