D_C_check: Internal function for formatting and checking specification...
In mvGPS: Causal Inference using Multivariate Generalized Propensity Score

Internal function for formatting and checking specification of exposures and confounders

1	D_C_check(D, C, common)

`D`	numeric matrix of dimension n by m designating values of the exposures
`C`	either a list of numeric matrices of length m of dimension n by p_j designating values of the confounders for each exposure value or if `common` is TRUE a single matrix of of dimension n by p that represents common confounders for all exposures.
`common`	logical indicator for whether C is a single matrix of common confounders for all exposures. default is FALSE meaning C must be specified as list of confounders of length m.