Patent ID: 8884954

Claim:
A computer software product for directly determining parameters defining a Weierstrass-Mandelbrot (W-M) analytical representation of a rough surface scalar field with fractal character, embedded in a three dimensional space, utilizing pre-existing measured elevation data of a rough surface in the form of a discrete collection of data describing a scalar field at distinct spatial coordinates, the product comprising a non-transitory physical computer-readable medium including stored instructions that, when executed by a computer, cause the computer to apply an inverse algorithm to the elevation data to thereby determine the parameters that define the analytical and continuous W-M representation of the rough surface, and wherein the surface has an array of elevation or height measurements z ij e , i, j=1 . . . K over a square region of size L×L and the parameters are γ and φ mn of the surface z(x, y) and the surface is represented by the complex Weierstrass-Mandelbrot (W-M) function W as: W ⁡ ( x ) = ∑ n = - ∞ ∞ ⁢ γ ( D - 2 ) ⁢ n ⁡ ( 1 - ⅇ ⅈγ n ⁢ x ) ⁢ ⅇ ⅈϕ n ( 1 ) where x is a real variable, and where a two dimensional profile obtained from the real part of Eq. 1 is: z ⁡ ( x ) = Re ⁡ [ W ⁡ ( x ) ] = ∑ n = - ∞ ∞ ⁢ γ ( D - 2 ) ⁢ n ⁡ [ cos ⁢ ⁢ ϕ n - cos ⁡ ( γ n ⁢ x + ϕ n ) ] . ( 2 ) and where D is the fractal dimension (1<D<2 for line profiles), φ n , is a random phase that is used to prevent coincidence of different phases, n is the frequency index and γ is a parameter that controls the density of the frequencies, and wherein the instructions include applying a Singular Value Decomposition (SVD) algorithm to a refactoring of Eq. (1), thereby determining said parameters of the Weierstrass-Mandelbrot (W-M) function describing the surface originally given in terms of measured elevation data.