How can i ignore a trend for the first part of an array?

Hi, I have an array which represents a change of altitude values:

A = [0,10,50,100,170,230,300,400,500,600,700,450,250,220,200,190,180]

I want to find the index of the values which are less than 240. In the above array, we have 2 solutions: either the number 230 which is index 6 or number 220 which is index 14. How can i ignore the first index so that in the end i always get the second index which is 14 ?

My trend is always increase of altitude, then decrease of altitude..

Answer 1

[KSSV]

To find the indices which are less then 240 use:

idx = find(A<240) ;  % idx are the indices