Iterating through 2 Arrays and Performing a Calculation

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Graduate Student
Graduate Student 2020-3-6
回答： Sindar 2020-3-6
A1 = [5 10 15 20 25 30 35 40]
A2 = [ 7 22 38]
Goal: Iterate through A2 and subtract from appropriate value in A1, store this value in a separate array.
Example:
7 in A2 is between 10 and 5 where
t1= 5
t2 = 10
Subtract A2 from t1.
7-5 = 2 (store this value in a separte array.
Move on to the second element in A2, 22. 22 is between 20 and 25. Substract (22-20) = 2; store this value
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Sindar
Sindar 2020-3-6
编辑：Sindar 2020-3-6
Ah, sorry, I asked the wrong question: Will A2 ever have elements less than all the elements in A1? (so t1 doesn't exist). Also, how many elements, roughly, will A1 and A2 have?
Graduate Student
Graduate Student 2020-3-6
There are about ~1000 elements in each array although each array is a different length from each other. No, A2 will not be less than A1. Thanks!

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Sindar
Sindar 2020-3-6
loop version:
for ind=1:length(A2)
idx = find(A1 < A2(ind),1,'last');
A3(ind) = A2(ind) - A1(idx);
end
Another (probably much worse) way of looking at it for smallish arrays:
A1 = [3 10 15 20 25 30 35 40];
A2 = [ 7 22 38];
% create a matrix of all combinations of A1(i)-A2(j)
tmp = A2-A1';
% set any less than zero to infinity
tmp(tmp<0)=Inf;
% find the minimum for each column
A3 = min(tmp)

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