Plotting a column of a matrix as function of the others

As the result of a computation, I have a Nx3 matrix (N is huge). The first column is called X, the second column is called Y and the third column is called Z. I want to plot Z as a function of X and Y, but there's no any particular order in the rows of the matrix and there might be repetitions. I would like to do two things:

1) Plot Z thridimensionally, as in a surface plot

2) Make a color map

How can I do this?

Thanks

Answer 1

[monika shivhare]

make a meshgrid using values of X and Y

[x,y] = meshgrid(X,Y);

make a surfaceplot

surf(x,y,Z)

refer to link surface plots

to make a colormap to the surfaceplot refer Change Color Scheme Using a Colormap

[Diego Soler Polo]

X and Y are so large (they have about 7 million components each) that this doesn't work (MATLAB cannot create the grid). Is there any other way around this?