How can I interpolate the 2-dimensional data

I have data like this

   1  2  3  4  5
1 81 83 85 87 90
2 84 N  88 90 92
3 83 85 86 N  91
4 86 87 88 92 94
5 88 89 90 96 99

How can I interpolate values for N?

Answer 1

[KL]

something like this maybe,

a = [81 83 85 87 90
  84 0  88 90 92
  83 85 86 0  91
  86 87 88 92 94
  88 89 90 96 99];
 a = a(:);
 x = 1:numel(a);
 xq = find(a==0);
 x(a==0)=[];
 a(a==0)=[];
 interp1(x,a,xq)

ans =

     84
     91

Answer 2

[John D'Errico]

1. Download inpaint_nans from the file exchange.

2. Substitute NaN for the elements indicated with an N.

3. Use inpaint_nans.