How to compare a number with values of a vector?

I have a vector. For example

A = [20 40 60 80 100 120]

I have a number as an input in a function

function imp(omega)

I need to compare the number omega with all the numbers of the vector. For example, the number is 30. I know 30 is in between 20 and 40. How do I find that by code?

Answer 1

[Fangjun Jiang]

A = [20 40 60 80 100 120];
x=30;
lowB=interp1(A,A,x,'previous')
HighB=interp1(A,A,x,'next')