55. polynomial — Polynomials

This module defines the class Polynomial, representing a polynomial in n variables.

Classes defined in module polynomial

class polynomial.Polynomial(exp, coeff=None)

A polynomial in ndim dimensions.

Parameters:

• exp: (nterms,ndim) int array with the exponents of each of the ndim variables in the nterms terms of the polynomial.
• coeff: (nterms,) float array with the coefficients of the terms. If not specified, all coeeficients are set to 1.

Example:

>>> p = Polynomial([(0,0),(1,0),(1,1),(0,2)],(2,3,-1,-1))
>>> print(p.atoms())
['1', 'x', 'x*y', 'y**2']
>>> print(p.human())
2.0 + 3.0*x -1.0*x*y -1.0*y**2
>>> print(p.evalAtoms([[1,2],[3,0],[2,1]]))
[[ 1.  1.  2.  4.]
 [ 1.  3.  0.  0.]
 [ 1.  2.  2.  1.]]
>>> print(p.eval([[1,2],[3,0],[2,1]]))
[ -1.  11.   5.]

degrees()

Return the degree of the polynomial in each of the dimensions.

The degree is the maximal exponent for each of the dimensions.

degree()

Return the total degree of the polynomial.

The degree is the sum of the degrees for all dimensions.

evalAtoms1(x)

Evaluate the monomials at the given points

x is an (npoints,ndim) array of points where the polynomial is to be evaluated. The result is an (npoints,nterms) array of values.

evalAtoms(x)

Evaluate the monomials at the given points

x is an (npoints,ndim) array of points where the polynomial is to be evaluated. The result is an (npoints,nterms) array of values.

eval(x)

Evaluate the polynomial at the given points

x is an (npoints,ndim) array of points where the polynomial is to be evaluated. The result is an (npoints,) array of values.

atoms(symbol='xyz')

Return a human representation of the monomials

human(symbol='xyz')

Return a human representation

Functions defined in module polynomial

polynomial.polynomial(atoms, x, y=0, z=0)

Build a matrix of functions of coords.

• atoms: a list of text strings representing a mathematical function of x, and possibly of y and z.
• x, y, z: a list of x- (and optionally y-, z-) values at which the atoms will be evaluated. The lists should have the same length.

Returns a matrix with nvalues rows and natoms colums.

polynomial.monomial(exp, symbol='xyz')

Compute the monomials for the given exponents

• exp: a tuple of integer exponents
• symbol: a string of at least the same length as exp

Returns a string representation of a monomial created by raising the symbols to the corresponding exponent.

Example:

>>> monomial((2,1))
'x**2*y'