Filtering values from a curve

I have a curve x vs. y and I'm reading into Matlab through excel (xlsread).

I want to filer some values off. I want to filter the y (and corresponding x of course) which are greater than a ceratin value (1500).

How can I achieve this please?

Please help...I shall be grateful

Answer 1

[Wayne King]

Sounds like you want to remove y-values greater than a certain value.

One way:

idx = find(y>1500);
% now remove the y values and the corresponding x-values
y(idx) = [];
x(idx) = [];

Note that if your x-values were originally evenly-spaced, the above will alter that spacing. Not sure if that is important. There are other things you can do that will preserve the equal spacing. For example, you can set y-values greater than 1500 to NaN (not a number)

y(y>1500) = NaN;