Find minimum of $n$ first entries, with $1\leq n\leq numel(X)$.

Given a one-dimensional array $X$, is there a fast way (faster than a for loop) to find $min_{1\leq m\leq n} X(m)$ for all $1\leq n\leq numel(X)$?

[Adam]

Can you give an example of what you are asking for? And preferably in words as semi-symbols are confusing!

[Bananach]

Given X=[4,3,2,5,7,0] I want Y=[4,3,2,2,2,0]

Answer 1

[Mischa Kim]

Bananach, use min :

X = rand(1,10)
X =
  0.6557    0.0357    0.8491    0.9340    0.6787    0.7577    0.7431    0.3922    0.6555    0.1712

min_X = min(X(1:6))  % find the minumum of the first 6 entries
min_X =
  0.0357

[Bananach]

I should have been more clear: I want a vector that contains the minimum for all possible values of 6 ;) That means, in your example, that I want a vector with 10 elements, with the entries $(min(X(1:j)))_{j=1}^10$

Answer 2

[Adam]

Y = cummin( X );

will do the job. There are a few in that family of functions that do cumulative analysis on a vector.