matrix addition different dimension using for loops.

조회 수: 5 (최근 30일)
Malini Bakthavatchalam
Malini Bakthavatchalam 2020년 8월 15일
댓글: Walter Roberson 2020년 8월 16일
Hi,
I am trying to do matrix addition of 2*4 to fit in 4*4 matrix. I am using for loops to get me familiarize with loops so that i can use it for image matrix manupulation. But with my code my output is 2*4 instead of 4*4.. could someone explain me the concept or the logic i am lacking here ..
a = [11:14; 15:18];
b = [3 2 3 1; 2 1 1 1;1 3 3 2; 2 1 1 3];
for i = 0
for j = 0
for x = 1:2
for y = 1:4
c(i+x,j+y) =b(i+x,j+y)+a(x+i,y+j);
end
end
end
end
  댓글 수: 2
Walter Roberson
Walter Roberson 2020년 8월 16일
If the first matrix were
1 2 3 4
5 6 7 8
and the second matrix was all zero, then what would you want the result of the addition to be ?
Malini Bakthavatchalam
Malini Bakthavatchalam 2020년 8월 16일
1 2 3 4
5 6 7 8
1 2 3 4
5 6 7 8
This would be my resultant matrix

댓글을 달려면 로그인하십시오.

채택된 답변

Walter Roberson
Walter Roberson 2020년 8월 16일
%this code will fail if a or b is empty, or if one size is not an exact multiple of the other
asz = size(a);
bsz = size(b);
maxsz = max(asz,bsz);
arep = maxsz ./ asz;
brep = maxsz ./ bsz;
ar = repmat(a, arep);
br = repmat(b, brep);
c = ar + br;
That is, create new matrices that contain the old matrices copied as many times as needed.
  댓글 수: 3
Walter Roberson
Walter Roberson 2020년 8월 16일
편집: Walter Roberson 2020년 8월 16일
ar = repmat(a, arep);
can be replaced with
[arows, acols, apanes] = size(a);
ar = zeros(arows*arep(1), acols*arep(2), apanes, class(a));
for J = 1 : arep(1)
arows = (J-1)*arows+1 : J*arows;
for K = 1 : arep(2)
acols = (K-1)*acols+1 : K*acols;
ar(arows, acols, :) = a;
end
end
Walter Roberson
Walter Roberson 2020년 8월 16일
I fixed a typing mistake in setting the class of ar

댓글을 달려면 로그인하십시오.

추가 답변 (0개)

카테고리

Help CenterFile Exchange에서 Creating and Concatenating Matrices에 대해 자세히 알아보기

Community Treasure Hunt

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

Start Hunting!

Translated by