How to write a grads executable file?

Here is my MATLAB code for saving a variable in .grd format, so that i can able to plot in grads with the help of control file. this is my long program. The line in where I have commented as 'DOUBT 1' is my doubt. P.S.: Dont go through the program, otherwise you will confuse in understanding the steps. My main doubt is in writing the gridded file.

   clc
  clear
  lon=ncread('2010110512-Jal-9km-bogus-r60km.nc','lon');
  lat=ncread('2010110512-Jal-9km-bogus-r60km.nc','lat') ;
  ntime=ncread('2010110512-Jal-9km-bogus-r60km.nc','time');
  u=ncread('2010110512-Jal-9km-bogus-r60km.nc','u');
  time=length(ntime)
  one_degree=round(1/(lat(2)-lat(1)));
  coc=[9.5,87];
  no_of_radius=15;
  h=waitbar(0,'Please wait...');

for k =1:25  %for time step 25
    waitbar(k/25)
  u1=u(:,:,:,k);
 if k==1
 for i=1:13
   i
   u2=u1(:,:,i);

if i==1
    [lat2,lon2]=cyclonic_modified1(coc(1),coc(2),no_of_radius);   
    for i=1:no_of_radius
        U(:,i)=interp2(lon,lat,u2,lon2(:,i),lat2(:,i));
    end

else
    [lat2(:,:,i),lon2(:,:,i)]=cyclonic_modified1(coc(1),coc(2),no_of_radius);
    for j=1:no_of_radius
     U(:,j,i)=interp2(lon,lat,u2,lon2(:,i),lat2(:,i));
   end
end
end

   else
        for i=1:13

     u2=u1(:,:,i);
  if i==1
      [lat2,lon2]=cyclonic_modified1(coc(1),coc(2),no_of_radius);   
      for i=1:no_of_radius
          U2(:,i)=interp2(lon,lat,u2,lon2(:,i),lat2(:,i));
      end

else
    [lat2(:,:,i),lon2(:,:,i)]=cyclonic_modified1(coc(1),coc(2),no_of_radius);
    for j=1:no_of_radius
     U2(:,j,i)=interp2(lon,lat,u2,lon2(:,i),lat2(:,i));
   end
end
      end
U(:,:,:,k)=U2;         %  -------------------------------------------------------------------------------DOUBT 1
 end

[~,I1]=min(abs(lat-coc(1)));
[~,I2]=min(abs(lon-coc(2)));
lat_range=[I1-round(one_degree/2):I1+round(one_degree/2)];
lat_range(lat_range<=0)=1;
lon_range=[I2-round(one_degree/2):I2+round(one_degree/2)];
lon_range(lon_range<=0)=1;
lat1=lat(lat_range);
lon1=lon(lon_range);
rain1=u(lon_range,lat_range);
[r,c]=minmat(rain1);
r=lat1(r);
c=lon1(c);
coc=[r,c];

end
fpo=fopen('jal_cyclone1.grd','wb');
 fwrite(fpo,U,'float32');
 fclose(fpo);

Every time my loops runs, it store U as 360*15*13*k where k starts from 1 to 25 After my loops ends, U has dimension 360*15*13*25 360*15 is the for the circular plot. 360 is degree and 15 is the circular radius. 13 is number of levels and 25 is number of time steps. How to write in a grid file so that it can be execute in grads.

P.S. If I save only 360*15 separately in a file, then i can able to plot in grads (The picture I have attached). But how to save as levels and different time steps. I can make a grads control file but there is an error in writing the grid file.

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/fileexchange/20880-surfer-grid-import-export