r.surf.fractal

	GRASS module to create a fractal surface of a given fractal dimension.
	Uses spectral synthesis method. Can create intermediate layers showing
	the build up of different spectral coefficients (see Saupe, pp.106-107
	for an example of this).

	Reference:

	Saupe, D. (1988) Algorithms for random fractals, in Barnsley M., 
		Devaney R., Mandelbrot B., Peitgen, H-O., Saupe D., and Voss R.
		(1988) The Science of Fractal Images, Ch. 2, pp.71-136. London:
		Springer-Verlag.

Jo Wood, 19th October, 1994

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Usage:
 r.surf.fractal out=name [d=value] [n=value]

Parameters:
  out   Name of fractal surface raster layer
    d   Fractal dimension of surface (2 < D < 3)
        default: 2.05
    n   Number of intermediate images to produce
        default: 0