how to find y axis value's opposite x axis value

for ex:x=1,2,3,4,5,6;y=2,7,8,9,4,1 i want pick up the y axis (9) opposite x axis value

Answer 1

[KL]

If both vectors are of same size, find the index of your variable from y and use it to pick the value at that position in x. A simple example is

 x = [1 2 3 4];
 y = [5 6 7 8];
 ind = find(y==7);
 x(ind);

[Stephen23]

Using logical indexing (as per Ilham Hardy's answer) is simpler and faster than using find.

[KL]

agreed.

Answer 2

[Ilham Hardy]

>> x=[1,2,3,4,5,6];
>> y=[2,7,8,9,4,1];
>> opp_x = x(y==9)

opp_x =

       4