Spline -- from Wolfram MathWorld

A piecewise polynomial function that can have a locally very simple form, yet at the same time be globally flexible and smooth. Splines are very useful for modeling arbitrary functions, and are used extensively in computer graphics. Cubic splines are implemented in the Wolfram Language as BSplineCurve[pts, SplineDegree -> 3] (red), Bézier curves as BezierCurve[pts] (blue), and B-splines as BSplineCurve[pts].

Ray-tracing simulation method using piecewise quadratic interpolant for aspheric optical systems

Pyramidal Frustum, PDF, Area

What software do you use for showing graphs and equations? - Quora

What software do you use for showing graphs and equations? - Quora

Line -- from Wolfram MathWorld, line

Basic Curves and Surface Modeling - CAD, PDF, Spline (Mathematics)

Create Graphics with Spline Primitives—Wolfram Language Documentation

Cubic Spline -- from Wolfram MathWorld

Least Squares Fitting -- from MathWorld

Unconstraint Optimization, PDF, Mathematical Optimization

Line -- from Wolfram MathWorld, line

Cubic Spline -- from Wolfram MathWorld