Package Exports
- cubic-roots
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Readme
cubic-roots
Implementation of Kahan's cubic root finder.
Motivation
According to Kahan, standard cubic root finders based on classical methods are prone to numerical inaccuracies. This is an implementation of a numerically stable method illustrated in Kahan's notes titled "To Solve a Real Cubic Equation".
The notes can be found here: http://people.eecs.berkeley.edu/~wkahan/Math128/Cubic.pdf.
Usage
The quadratic equation solved is Ax2 + Bx + C = 0. The cubic equation solved is Ax3 + Bx2 + Cx + D = 0.
- getQuadraticRoots(A, B, C)
- returns 4 real numbers: A1, B1, A2, B2
- this corresponds to the (possibly) complex roots A1 + B1 * i and A2 + B2 * i.
- getCubicRoots(A, B, C, D)
- returns 5 real numbers: A0, A1, B1, A2, B2
- this corresponds to the 1 real and 2 (possibly) complex roots A0, A1 + B1 * i, and A2 + B2 * i.
Author
Algorithm and pseudocode by William Kahan. Implementation in Javascript by Tim Bright
License
(c) Tim Bright, 2017. MIT License.