inverse vector fields obtained by optical flow

How can I invert a vector field(vf)?vf's inverse is not unique and need to be estimated in an optimal manner like fixed point iteration or any other iteration techniques. I wrote a code and want you to check it if it's correct or not. if true function p=testfixpointt(v) [N,M]=size(v); p(1:N,1:M,1)=0; conv=1e-5; err=1; n=1; while err>conv for i=1:N for j=1:M if (i+p(i,j,n)==0 j+p(i,j,n)==0) continue end if (abs(i+p(i,j,n))>N ||abs(j+p(i,j,n))>M) continue end p(i,j,n+1)=-v(ceil(abs(i+p(i,j,n))),ceil(abs(j+p(i,j,n)))); end end err=abs(p(:,:,n+1)-p(:,:,n)); n=n+1; end end

[Yash]

if you can post the code using the code posting method in this forum then this will be good.