define x and y for interpolation of scattered data

I have the following data in excel, which is a 20*20 table. I need to interpolate base on available data for the whole table. So, I wanna know how to define x and y of the data in the following code.

numdata = xlsread ('basic file');
x= 
y=
[xq,yq] = meshgrid(1:1:20, 1:1:20);
vq = griddata(x,y,v,xq,yq,'nearest');

Answer 1

[KSSV]

Let A be the matrix, which is of size m*n

x = 1:n ; 
y = 1:m ; 
[X,Y] = meshgrid(x,y) ; 
xq = 1:0.5:n ; 
yq = 1:0.5:m ; 
[Xq,Yq] = meshgrid(xq,yq) ; 
Ai = interp2(X,Y,A,Xq,Yq) ; 

Alrernatively, you can also use

Ai = imresize(A,[100,100]) ;