sign-changes
▸ function signChanges
(p: number[]): number
Defined in roots/descartes/double/sign-changes.ts:25
Returns the number of sign changes in the polynomial coefficents when ordered in descending order; zeros are ignored.
Descartes' rule of signs states (quoted from Wikipedia): "if the terms of a polynomial are ordered by descending variable exponent, then the number of positive roots of the polynomial is either equal to the number of sign differences between consecutive nonzero coefficients, or is less than it by an even number. Multiple roots of the same value are counted separately."
example
signChanges([1,2,-3,0,0,3,-1]); //=> 3
Parameters:
| Name | Type | Description |
|---|---|---|
p | number[] | a polynomial with coefficients given densely as an array of double floating point numbers from highest to lowest power, e.g. [5,-3,0] represents the polynomial 5x^2 - 3x |
Returns: number