You have three single column variables X, Y and Z containing (respectively) Easting, Northing and elevation values.

You want to present the data as a surface, but you know you cannot use these data directly.

Give name of the command that has to be applied to the X, Y and Z values to generate the surface data that can be directly plotted by command surf. This command takes the X, Y and Z data and values of x and y in the required mesh, and produces suitably interpolated elevation data.