Resolution of surface

I need to put this function (f) in a matrix to print it as a figure, but how can I put it in the same matrix (4001, 3001) with two resolutions (1um, 2um) and the same wavelength 100um?
May someone please help me in solving this query.

f = @(x) 3*sin(x*2*pi/wavelength) + 1003      % The function for the sine wave with the 
  % amplitude 3 µm and wave length of about 100 µm     
  % Mean level is 1003 µm