I need to calculate matrix b for each iteration from k value 0 to 1 with the step size of 0.01. How can I calculate the iteration using the for loop function and store all iteration outputs in matrix? Somebody please help me. Thank you.

load acetylene

X= [x1,x2,x3];

k =1;

I=eye(size(X'*X));

b=((inv(X'*X+k*I))*X')*y;

for i=0:0.01:1

    b(i)=((inv(X'*X+k(i)*I))*X')*y;
  end

This is the code and I got the error message as below.

Attempted to access k(0); index must be a positive integer or logical.

Error in berlatih6 (line 14)

    b(i)=((inv(X'*X+k(i)*I))*X')*y;

Answer 1

[Walter Roberson]

Generally speaking you should transform

for i = list of floating point values
  calculation that produces one result for each i
end

to

ivals = list of floating point values
for J = 1 : length(ivals)
  i = ivals(J);
  outputvariable(J) = ....
end

except that you should avoid using a variable named "i" as "i" is the imaginary unit.

[Ahmad Zul Izzi Fauzi]

Hi Walter, Thank you for your answer. But I got this error message too.

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

[Walter Roberson]

outputvariable{J} = ....

If you want the results in an array then you will have to define which dimension the various values should be on. For example it is plausible that you want

outputvariable(:,:,J) = ....

but since we have no idea what the size() are of your variables or how you want the output arranged we can't say for sure.

[Ahmad Zul Izzi Fauzi]

Thank you very much. It works now.

Answer 2

[Roger Stafford]

As you can determine by reading the Matlab documentation, you cannot have zero or fractional values for array indices as you have done in k(i) and b(i). You should do this instead:

   k = 0:0.01:1;
   b = zeros(length(k),1);
   for ii = 1:length(k)
     b(ii)=((inv(X'*X+k(ii)*I))*X')*y;
   ...

[Ahmad Zul Izzi Fauzi]

Thank you for your answer. Now I got this error message.

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