# polyder

## Purpose

Polynomial derivative.

## Synopsis

    k = polyder(p)
    k = polyder(a,b)
    [q,d] = polyder(b,a)

## Description

`k = polyder(p)`, where `p` is a vector whose elements are the coefficients of a polynomial in descending powers, returns the derivative of that polynomial. `k` is a vector containing the coefficients of the derivative in descending powers.

`k = polyder(a,b)` returns the derivative of the product of the polynomials `a` and `b`.

`[q,d] = polyder(b,a)` returns the derivative of the polynomial quotient `b/a`, where the derivative is represented by `q/d`.

## Examples

The derivative of the product

is obtained with

    a = [3 6 9];
    b = [1 2 0];
    k = polyder(a,b)

    k =
        12    36    42    18

This result represents the polynomial

(c) Copyright 1994 by The MathWorks, Inc.