Increasing speed to perform binary read/write operations

Hello everyone. I have a big binary file with a ascii header. In binary part I have a data which I need to change, smooth etc. Read part is looks like:

fid1=fopen(path,'rb','l');
for ii=1:ramp
    skbytes=begbytes+skip+(ii-1)*skip+(ix-1)*nx*ncol+(iy-1)*nx;
    fseek(fid1,skbytes,'bof');
    ax=fread(fid1,[1 1],sh);
    aax=double(ax);
    yiv(ii,1)=aax;
end
fclose(fid1);

The writing part is the next:

fid=fopen(path1,'r+','l'); 
for kk=1:ramp
            skbytes=begbytes+skip+(ix-1)*ncol*nx+(iy-1)*nx+(kk-1)*skip;
            fseek(fid,skbytes,'bof');
            fwrite(fid,smy(kk,1),sh);
end
clear kk;
fclose(fid);

The problem is I have 128x128 numbers of these curves. And it is required 3 hours to perform all calculations.

I will be thankful for any idea or help with this.

[Dima Lotnik]

I also tried to use memmapfile function. But the time to create a single curve is almost the same. The code I use is below:

   m = memmapfile('path','Offset',beg,'Format',{'int16',[ncol nrow],'mj'},'Repeat',ramp+1, 'Writable', true);
   for ii=1:ncol
       tic;
       for jj=1:nrow 
           for kk=1:ramp
                   iv(kk,1)=m.data(kk+1).mj(ii,jj);
           end
       end
       toc;
   end