[R] interpolation function

[=?gb2312?B?zuIg6rs=?=]

Hi,
I have a sparse matrix.I want to fill values into the entries whose value 
is 0.The new generated values should come from the interpolation of the 
values have existed.Does R provide such interpolation functions which 
operate on Matrix, for example ,such a matrix below
 0  0  0  0  2.3  0 0  0  0 
 0  0 3.1 0   0   0 0 1.4 0
 0  0  0  0   0   0 0  0  0
1.1 0  0  0   0   0 0  0  0
 0  0  0  4   0   0 0  0  6
 0  0  0  0   0   0 0  0  0
 0  0  0  0   0   7 0  0  0
 0  3  0  0   0   0 6  0  0
 0  0  0  0   9   0 0  0  0
thanks a lot
hao wu