polyder

Polynomial Differentiation

Usages

q = polyder(p)

• The input p should be a vector, real or complex, containing coefficients of the polynomial with p(1) and p(end) being the highest and the zeroth order terms, respectively:

• The output q contains the coefficients of the derivative

q = polyder(a,b)

• The inputs a and b should be vectors, real or complex, containing coefficients of the polynomials $a(x)$ and $b(x)$, respectively.
• The output q is the derivative of the product $a(x)b(x)$, i.e.,

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

• The inputs a and b should be vectors, real or complex, containing the coefficients of the polynomials $a(x)$ and $b(x)$, respectively.
• The outputs q and d represent the polynomials $q(x)$ and $d(x)$, which are, respectively, the numerator and denominator of the derivative of the quotient $a(x)/b(x)$:

Examples

• Differentiating $x^4+2x^3+3x^2+4x+5$ gives $4x^3+6x^2+6x+4$.

Input

polyder(1:5)

Output

ans =
4.000   6.000   6.000   4.000

• polyder(a, b) differentiates the product of the polynomials given by a and b.

Input

% Derivative of the product of a and b.
a=1:5;
b=1:2;
q1 = polyder(a, b)
% The above is the same as differentiation 
% after polynomial multiplication using conv().
q2 = polyder(conv(a, b))

Output

q1 =
 5.000   16.00   21.00   20.00   13.00

q2 =
 5.000   16.00   21.00   20.00   13.00

Differences with MATLAB