The E-M algorithm is explained in section 13.2.4.
The calling syntax for
`software/gmix_step.m` is as follows:
[gparm,Q] = gmix_step(gparm,x, [bias],[data_wts]);

where `gparm` are the input parameters,
`x` is the normalized input data, `bias`
(optional) is set to 1 for BIAS method and 0 for CONSTRAINT method,
and `data_wts` (optional) allows individually weighting input data.
On return, `Q` is the total log-likelihood.

Baggenstoss
2017-05-19