Makes plot of the precision matrix showing non-zero values. The diagonal is shown in only black because the agreement with itself is not highly interesting. Negative relations are shown in green and positive in red. The saturation indicates the normalized strength of the relation. The matrix is symmetric and technically only the lower or upper triangle would suffice to provide identical information.
The BigQuic object, which will have its optimal precision matrix plotted.
plot can take a variety of arguments depending on the type, that is represented by ...