Finding corresponding interpolated x values for defined y values

Hi all,

I have obtained data and plotted it. I then interpolated it via spline interpolation and everything works fine. However, I would like to obtain precise values for the t2 (i.e. the interpolated x values) coordinates at say 10%, 20%, 30% etc., of the maximum y2 (i.e. interpolated y values) value.

The answer I obtain is

ans =

     Empty matrix: 1-by-0

Please see the code below. I hope you can help.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
x = KE_data(:,1);   
y = KE_data(:,2);   

t2 = -20.5005:0.00002457:-20.2548; 
y2=interp1(x,y,t2);

max_y2 = 0.1*max(y2);

t2((y2==max_y2))

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[Susan]

Many thanks, Walter