Multiple Linear Regression
            IMSL_MULTIPREDICT: Computes predicted values, confidence intervals, and diagnostics.
            IMSL_MULTIREGRESS: Fits a multiple linear regression model and optionally produces summary statistics for a regression model.
            IMSL_REGRESSORS: Generates regressors for a general linear model.
            Variable Selection
            IMSL_ALLBEST: All best regressions.
            IMSL_STEPWISE: Stepwise regression.
            Polynomial and Nonlinear Regression
            IMSL_NONLINREGRESS: Fits a nonlinear regression model.
            IMSL_POLYPREDICT: Computes predicted values, confidence intervals, and diagnostics.
            IMSL_POLYREGRESS: Fits a polynomial regression model.
            Multivariate Linear Regression: Statistical Inference and Diagnostics
            IMSL_HYPOTH_PARTIAL: Construction of a completely testable hypothesis.
            IMSL_HYPOTH_SCPH: Sums of cross products for a multivariate hypothesis.
            IMSL_HYPOTH_TEST: Tests for the multivariate linear hypothesis.
            Polynomial and Nonlinear Regression
            IMSL_NONLINOPT: Fit a nonlinear regression model using Powell's algorithm.
            Alternatives to Least Squares Regression
            IMSL_LNORMREGRESS: LAV, Lpnorm, and LMV criteria regression.