Matrix functions

Matrix functions are used to perform matrix calculations, like matrix multiplication or matrix inverse.

• matrix multiplication (also: matr_mul)
• matrix inverse (also: matr_inv)
• matrix covariance (also: matr_var)

How these functions combine into regression models, with configurations that run as given for an ordinary least squares regression, a binomial logistic regression and a multinomial logit model: Linear and logistic regression.