Three pairs random numbers between 0 and 1 are obtained. These pairs refer to the x, y and z coordinates of the nodes respectively. The first random number of each pair is multiplied by the factor given in thecommand. The second random number is used to determine if the calculated offset is to be added or subtracted from the coordinate. No checking is done to see if elements are inverted by this perturbation.  It is assumed that the mesh is not yet connected.