You can use a combination of meshgrid and griddata to do this. In the code below, I'm assuming that x is a column vector with the x coordinates of all of your points, y is a column vector with the y coordinates of all of your points, and z is a column vector with the z coordinates of all of your points.
dx=linspace(min(x),max(x),n);%n is the number of columns you want in your grid
dy=linspace(min(y),max(y),m);%m is the number of rows you want in your grid
[xq yq]=meshgrid(dx,dy);
grid=griddata(x, y z, xq, yq, 'linear');%linear is the type of interpolation used
The documentation for griddata also provides more examples: https://www.mathworks.com/help/matlab/ref/griddata.html
