# If statement without loop

4 views (last 30 days)
Hokkien on 27 Dec 2021
Commented: Hokkien on 27 Dec 2021
Hi there are two questions I wish to ask:
First, I would like to use if else statement without the loop. Here is my attempt with the loop:
for k=1:15
for j=1:10
if A(j,k) > B(j,1), C(j,k)=0;
else
C(j,k)=A(j,k);
end
end
end
toc;
This took some computation time but I wish to cutdown the time. I attempt to use:
TR1_Ge70(TR>TR_Ge&)=0;
However, the matrix dimension is incorrect. Here is the example:
Matrix A Matrix B Matrix C
1 2 3 4 5 3 1 2 0 0 0
1 2 3 4 5 2 1 0 0 0 0
1 2 3 4 5 1 0 0 0 0 0
1 2 3 4 5 5 1 2 3 4 0
The second question will be bit massive and I fail to write one. I have a matrix A, let say 3 by 3. I also have matrix B, let say 3 by 3 as well. I wish to multiple the first column of matrix A with the entire matrix B, and the scond column and etc. For example:
Matrix A Matrix B Outcome using first column A: Outcome using second column B:
1 2 2 2 2 1 2 2 1 4 4 2
3 3 2 3 3 2 9 9 6 9 9 6
4 2 3 1 2 1 4 8 4 2 4 2
Based on this, I will get three set outcomes. However, it's seem like I cannot write the code and give me three different outcomes directly. The only way that I think is that I have to maintain only single column of Matrix A, and change it every time in order to get three different outcomes. Is it a quick way to do this? Thank you so much for the help!
##### 2 CommentsShowHide 1 older comment
Hokkien on 27 Dec 2021
Hi I'm using Matlab R2020b

Stephen23 on 27 Dec 2021
Edited: Stephen23 on 27 Dec 2021
A = repmat(1:5,4,1)
A = 4×5
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
B = [3;2;1;5]
B = 4×1
3 2 1 5
C = A;
C((1:5)>=B) = 0
C = 4×5
1 2 0 0 0 1 0 0 0 0 0 0 0 0 0 1 2 3 4 0
Hokkien on 27 Dec 2021
Thank you so much! I understand now!

David Hill on 27 Dec 2021
TR1_Ge70(TR1>TR1_Ge70(:,1))=0;
for k=1:size(A,2)
C(:,:,k)=A(:,k).*B;
end
Hokkien on 27 Dec 2021
Hi Thank you so much, unfornutately I still have dimension problem. I'm sorry if my question is not clear. I have re-edit it with the example:
Matrix A Matrix B Matrix C
1 2 3 4 5 3 1 2 0 0 0
1 2 3 4 5 2 1 0 0 0 0
1 2 3 4 5 1 0 0 0 0 0
1 2 3 4 5 5 1 2 3 4 0
Thank you!

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