Question

I am using the interp1 function to resample (a,b) to (new_a, new_b).
I get NAN for the values of new_b.
a, b are row matrices.
Some values in b are zero. How to get rid of this? Because of NAN I am unable to generate the correct plot for plot(new_a, new_b, ‘r*)

c = cat(1,a, b);
[s,i] = sort(c(1,:)); #Sort by the 1st row              
sort_ab = c(:,i);
sort_a = sort_ab(1,:);
sort_b = sort_ab(2,:);                                              

new_a = min(sort_a):0.001:max(sort_a);                                  
new_b = interp1(a, b, new_a);  

Answer 1

From http://www.mathworks.com/help/techdoc/ref/interp1.html:

For the 'nearest', 'linear', and
'v5cubic' methods,
interp1(x,Y,xi,method) returns NaN for
any element of xi that is outside the
interval spanned by x.

Note that 'linear' is the default interpolation method.

You haven’t provided us with the values of a and b, but the above sounds the most likely explanation.