getting an error ??? Subscript indices must either be real positive integers or logicals.

I run this code and i get the error at line 14 (at MAD=....)

function [fp,mvx,mvy]=vp_ipebma(f1,f2,N,R)

%f1: anchor frame; f2: target frame, fp: predicted image;

%mvx %mvx mvy: store the MV image ,mvy: store the MV image

%widthxheight: image size; N: block size (16 here), R: search range

height=352;

width=288;

i=0;

for i=N:N:height-N,

      for j=N:N:width-N  %for every block in the anchor frame

          MAD_min=256*N*N;mvx=0;mvy=0;

          for k=-R:1:R,
              for l=-R:1:R  %for every search candidate
                  MAD=sum(sum(abs(f1(i:i+N-1,j:j+N-1)-f2(i+k:i+k+N-1,j+l:j+l+N-1))));
                  %%calculate MAD for this candidate calculate MAD for this candidate
                  if MAD<MAD_min
                      MAD_min=MAD;
                      dy=k;
                      dx=l;
                  end
              end
          end
          fp(i:i+N-1,j:j+N-1)= f2(i+dy:i+dy+N-1,j+dx:j+dx+N-1); 
          %put the best matching block in the predicted image
          iblk=(floor)*(i-1)/N+1; 
          jblk=(floor)*(j-1)/N+1; 
          %block index
          mvx(iblk,jblk)=dx; 
          mvy(iblk,jblk)=dy; 
          %record the estimated MV
      end
  end
  imshow(uint8(fp));