I'm not sure if I'm interpreting your data correctly--it starts with "lat lon s" followed by a string of numbers. Do you mean
d1=[20.3250 50.1234 1.0000;
21.3690 51.2365 21.0000;
23.6987 52.6398 36.0000;
24.6980 53.6987 65.0000;
25.1456 56.2583 62.0000;
26.6987 54.2146 35.0000;
23.6589 52.3655 24.0000;
25.6358 58.9654 15.0000;
22.5698 57.3698 15.0000];
%
d2=[20.3610 50.1594 1.5000;
21.4050 51.2725 21.5000;
23.7347 52.6758 36.5000;
24.7340 53.7347 65.5000;
25.1816 56.2943 62.5000;
26.7347 54.2506 35.5000;
23.6949 52.4015 24.5000;
25.6718 59.0014 15.5000;
22.6058 57.4058 15.5000];
where column 1 is lat, column 2 is lon, and column 3 is your measured data? If so, there are a number of ways you can do this. If you want to associate round measurement station locations to the nearest hundredth-degree, you can get the latitudes of dataset 1 by
lat1 = round(100*d1(:,1))/100
=20.3300
21.3700
23.7000
24.7000
25.1500
26.7000
23.6600
25.6400
22.5700
[d1_grid,lon,lat] = gridfit(d1(:,2),d1(:,1),d1(:,3),50.1:.1:59.1,20.3:.1:26.8);
d2_grid = gridfit(d2(:,2),d2(:,1),d2(:,3),50.1:.1:59.1,20.3:.1:26.8);
figure
subplot(321)
pcolor(lon,lat,d1_grid)
shading interp
hold on
plot(d1(:,2),d1(:,1),'rp')
title('d_1','backgroundcolor','w','vert','top')
borders('countries','k','nomap')
subplot(322)
pcolor(lon,lat,d2_grid)
shading interp
hold on
plot(d2(:,2),d2(:,1),'rp')
borders('countries','k','nomap')
title('d_2','backgroundcolor','w','vert','top')
subplot(3,2,3:6)
pcolor(lon,lat,d2_grid-d1_grid)
shading interp
title('d_2 - d_1','backgroundcolor','w','vert','top')
borders('countries','k','nomap')
labelborders('countries','nomap')
