Name:   mk_vel  make a synthetic irregular velocity field

Type:   Data Input

Author: I. Curington, Advanced Visual Systems, Inc.

Language: C

Parameters:
    V Scale       height scale factor exageration
    Dx            array dimensions in X, Y, Z
    Dy
    Dz
    Randomness    0-1 variance from smooth to rough

Output:
    field 3D irregular scalar float

Description:

 This module generates a synthetic 3D field, with random
 perturbations in both coordinates and data values.
 The 3D scalar field is the square of the distance from
 a point on the center of the bottom plane.
 An isosurface of this is approximately a parabola.
 This was used in a demonstration of seismic velocity
 modelling.