write operation is not working and giving error

 file=aviinfo('vipmosaicking.avi')
frm_cnt=file.NumFrames
fileExtension='.bmp';
for i=1:frm_cnt
   frm(i)=aviread('vipmosaicking.avi',i)
   frm_name=frame2im(frm(i))
   filename=strcat('/home/computer/desktop/ivp_10/',strcatnum2str(i)),fileExtension)
   imwrite(frm_name,filename);
end

Answer 1

[Walter Roberson]

   filename = fullfile('/home/computer/desktop/ivp_10', sprintf('%d%s', i, fileExtension));