When find doesn't find any values > 0.999, it returns an empty vector, with a size of 0x1. Furthermore, max returns an empty vector even if the other value is a number. 0x1 empty vectors don't fit in a 1x1 slot like r(i,1).
The error text is often helpful: Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 0-by-1.
r1(i,1) = r
left side (1x1) right side (0x1)
You could test for the empty value and, for instance, convert it to a NaN:
if isempty(r)
r(i,1) = nan;
else
r(i,1) = r;
end
Incidentally, for your future reference, r(i) is equivalent to r(i,1) in this case (and L(i) to L(i,1)). Since the second dimension of r (and L) has size 1, the value only has one column in which it is possible to be placed.
