Cubic Spline Interpolation
            IMSL_CSINTERP: Derivative end conditions.
            IMSL_CSSHAPE: Shape preserving.
            B-spline Interpolation
            IMSL_BSINTERP: One-dimensional and two-dimensional interpolation.
            IMSL_BSKNOTS: Knot sequence given interpolation data.
            B-spline and Cubic Spline Evaluation and Integration
            IMSL_SPINTEG: Integration.
            IMSL_SPVALUE: Evaluation and differentiation.
            Least-squares Approximation and Smoothing
            IMSL_BSLSQ: Splines with fixed knots.
            IMSL_CONLSQ: Constrained spline fit.
            IMSL_CSSMOOTH: Cubic-smoothing spline.
            IMSL_FCNLSQ: General functions.
            IMSL_SMOOTHDATA1D: Smooth one-dimensional data by error detection.
            Scattered Data Interpolation
            IMSL_RADBE: Evaluates a radial-basis fit.
            IMSL_RADBF: Computes a fit using radial-basis functions.
            IMSL_SCAT2DINTERP: Akima’s surface-fitting method.