Cubic spline interpolation in SAS - The DO Loop

I recently showed how to use linear interpolation in SAS. Linear interpolation is a common way to interpolate between a set of planar points, but the interpolating function (the interpolant) is not smooth. If you want a smoother interpolant, you can use cubic spline interpolation. This article describes how to

How can I use PROC TRANSREG to generate splines in SAS?

The G3GRID Procedure : Using Partial Spline Interpolation

QGIS 101: Cubic Spline Interpolation of static water levels

Cubic splines to model relationships between continuous variables and outcomes: a guide for clinicians

Understanding cubic splines in JMP

The G3GRID Procedure : Using Spline Interpolation

Cubic Spline Interpolation - MATLAB & Simulink

Cubic Spline Interpolation - Timo Denk's Blog

SAS Help Center: SPLINE and SPLINEC Calls

Bicubic interpolation - Wikipedia

Regression with restricted cubic splines in SAS - The DO Loop

SAS/GRAPH Statements : SYMBOL Statement