extrapolate values from matrices and graphs

I have a chart of this type which derives from this script:

for i=1:length(longrd)
    for j=1:length(latgrd)
        XX(i,j)=longrd(i);
        YY(i,j)=latgrd(j);
        isel1=find(lonlatgrd(:,1)==longrd(i));
        isel2=find(lonlatgrd(isel1,2)==latgrd(j));
        isel=isel1(isel2);
        ZZ(i,j)=prob(isel);
    end
end
contourf(XX,YY,ZZ,500,'linecolor','none');
colormap jet
hold on
load coastlines.mat
geoshow(coastlat,coastlon,'color','k');
hold on
lonP = 14.2;
latP = 40.8;
plot(lonP,latP,'bo');           
hold on
lonP_t= 13.5;
latP_t= 41.9; 
plot(lonP_t,latP_t,'ro');       
xlim([min(longrd), max(longrd)]);
ylim([min(latgrd), max(latgrd)]);
colorbar;
pbaspect([1 1 1]);
xlim(limlon);ylim(limlat);

whereXX, YY and ZZ are 401x401 double, prob is 1x 160801 double.

from all this graph I would need to extract only the values relative to the point of coordinates lonP_t and LatP_t (shown in the figure), in particular I need to know the value of the Z axis. This value I have to be able to extrapolate it to combine it with other data and then use it in another graph .

Can anyone help me?

Answer 1

[KSSV]

I don't think it is extrapolation, it is interpolation. Read about interp2.

iwant = interp2(XX,YY,ZZ,lonP_T,latP_t)

[ELISABETTA BILLOTTA]

no I don't have to interpolate the values ... I have to get the value of lonP_t and latP_t which is already inside the ZZ matrix and therefore also in prob. this value then I have to use it externally. from the graph in the figure you can see the value I need (0.022 ..), so I have to view it and then save it and use it in other matrices.

[KSSV]

Try the give function.

[ELISABETTA BILLOTTA]

the script is written in this question