How to store vectors from each for loop in a matrix

Hi I have a for loop. The result of every iteration is a rowvector. I want all rowvectors of the for loop stored as one matrix. Each row is the result of one iteration.

Simplified example:

if true
X= 1:0.1:2;
for i = 1:length(X)
A=4
B= 1:5
Y= A.*X(i)+B
end
end

The end result shoud be an 11 x 5 matrix. Indexing will give errors, so will starting with an empty array.

[Bob Nbob]

What do you mean, 'Indexing will give errors?' What error message are you getting?

I was able to get the result to index just fine.

X= 1:0.1:2;
for i = 1:length(X)
A=4
B= 1:5
Y(i,:)= A.*X(i)+B
end

[Mike Mierlo van]

You Da Man!

I tried Y(i)=A.X(i)+B which was giving me a hard time. The ,: made the difference. Thank you!

[Stephen Cobeldick]

You do not need a loop, just

>> A*X(:) + B % for MATLAB >= R2016b

Or for earlier versions use bsxfun:

>> bsxfun(@plus,A*X(:),B)
ans =
    5.0000    6.0000    7.0000    8.0000    9.0000
    5.4000    6.4000    7.4000    8.4000    9.4000
    5.8000    6.8000    7.8000    8.8000    9.8000
    6.2000    7.2000    8.2000    9.2000   10.2000
    6.6000    7.6000    8.6000    9.6000   10.6000
    7.0000    8.0000    9.0000   10.0000   11.0000
    7.4000    8.4000    9.4000   10.4000   11.4000
    7.8000    8.8000    9.8000   10.8000   11.8000
    8.2000    9.2000   10.2000   11.2000   12.2000
    8.6000    9.6000   10.6000   11.6000   12.6000
    9.0000   10.0000   11.0000   12.0000   13.0000

[Mike Mierlo van]

For the simplified version this is OK. But in my sophisticated version is A and B an array too, so I think in that case an loop fits best.

Answer 1

[meghannmarie]

if true
    X= 1:0.1:2;
    A = 4;
    B = 1:5;
    Y = nan(length(X),length(B));
    for i = 1:length(X)
        Y(i,:) = A.*X(i)+B;
    end
end