Duplicate a matrix using nested for loops

조회 수: 2 (최근 30일)
Tyler M
Tyler M 2018년 2월 20일
댓글: Stephen23 2018년 2월 20일
In Matlab I have been trying to duplicate matrix A [2,4,1;6,7,2;3,5,9] to matrix B using nested for loops. I know the general format uses an algorithm within the loop ie.
m=3
n=3
b=zeros(m,n)
for i=1:m
for j=1:n
B(m,n)= *algorithm here*
end
end
I can not find an algorithm that would work for this matrix and I believe that it was designed this way on purpose. I have tried pulling numbers out of matrix A using
A=[2,4,1;6,7,2;3,5,9]
for c=A(1,:)
for d=A(2,:)
for e=A(3,:)
end
end
end
B=[c;d;e]
but this just assigns the values for the last column of A to a 1x3 matrix B (B=[1;2;9]
I have also tried scouring the www for help with how to duplicated a matrix that is not algorithmic using nested for loops to no avail.
Any help or guidance would be much appreciated.
  댓글 수: 1
Stephen23
Stephen23 2018년 2월 20일
???
Why not just avoid the pointless loops and use B=A ?

댓글을 달려면 로그인하십시오.

채택된 답변

Roger Stafford
Roger Stafford 2018년 2월 20일
What's wrong with
B = A; % ?
However, if you absolutely must do it with nested for-loops then do:
[m,n] = size(A);
B = zeros(m,n);
for i1 = 1:m
for i2 = 1:n
B(i1,i2) = A(i1,i2);
end
end
_
  댓글 수: 3
Roger Stafford
Roger Stafford 2018년 2월 20일
편집: Roger Stafford 2018년 2월 20일
You wouldn't want to use just B=A inside those for-loops. That would be extremely wasteful of computing time. B=A by itself does the job without for-loops. Using for-loops with B(i1,i2) = A(i1,i2); is bad enough.
Tyler M
Tyler M 2018년 2월 20일
I see your points. I will definitely keep these in mind while writing code in the future!

댓글을 달려면 로그인하십시오.

추가 답변 (0개)

카테고리

Help CenterFile Exchange에서 Loops and Conditional Statements에 대해 자세히 알아보기

제품

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by