Quadratic spline subroutine package
Water-Resources Investigations Report
82-41
By: Lowell A. Rasmussen
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Abstract
A continuous piecewise quadratic function with continuous first derivative is devised for approximating a single-valued, but unknown, function represented by a set of discrete points. The quadratic is proposed as a treatment intermediate between using the angular (but reliable, easily constructed and manipulated) piecewise linear function and using the smoother (but occasionally erratic) cubic spline. Neither iteration nor the solution of a system of simultaneous equations is necessary to determining the coefficients. Several properties of the quadratic function are given. A set of five short FORTRAN subroutines is provided for generating the coefficients (QSC), finding function value and derivatives (QSY), integrating (QSI), finding extrema (QSE), and computing arc length and the curvature-squared integral (QSK). (USGS)
Suggested Citation
Rasmussen, L.A., 1982, Quadratic spline subroutine package: U.S. Geological Survey Water-Resources Investigations Report 82-41, 16 p. , https://doi.org/10.3133/wri8241.
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Quadratic spline subroutine package |
| Series title | Water-Resources Investigations Report |
| Series number | 82-41 |
| DOI | 10.3133/wri8241 |
| Year Published | 1982 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Description | 16 p. |