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Calculate values only once in the loop

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D_coder
D_coder 2018-9-12
评论： D_coder 2018-9-12
Suppose I have a code running in a loop I have done some operations and I create a matrix in the loop, that matrix has the same size in every iteration. How do i calculate the number of elemens of the matrix only for the first iteration and not for every iteration since i know that it will be the same for every iteration? I want to avoid using ifelse statements.

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回答（2 个）

KSSV
KSSV 2018-9-12
Read about function numel. This will give you the number of elements present. Also you can get size of matrix and do product to get the elements.
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KSSV
KSSV 2018-9-12
N = 0 ; % number of elements
for i = 1:10
A = rand(10) ;
while ~N
N = numel(A) ;
end
end
D_coder
D_coder 2018-9-12
is there anyother way to calculate without using loops or if else statement. How about N(N==0) = execute the statement

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Amir Xz
Amir Xz 2018-9-12
Use "isempty":
I = rand(4,5);r=[]; c=[];
for i=1:10
if isempty(r) || isempty(c)
[r,c]=size(I);
end
end

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