precision_sfn: Precision matrix of scale free network
In spcorum/tsmvrdata: Datasets for tsmvr

Constructs a scale free network (SFN) precision matrix according to the Barabasi algorithm.

1	precision_sfn(q, n_edge = 1, shift = 1, power = 1, zero_appeal = 1)

`q`	square dimension of covariance matrix (positive integer)
`n_edge`	Barabasi algorithm number of edges per step for SFN covariance matrix (positive integer)
`shift`	eigenvalue shift parameter for SFN covariance matrix (`shift` > 0) (ensures matrix is PSD) )
`power`	scaling power for SFN covariance matrix (positive numeric)
`zero_appeal`	Barabasi algorithm baseline attractiveness for SFN covariance matrix (positive numeric)