UniVariatePolynomial

class UniVariatePolynomial(*args)

Base class for univariate polynomials.

Parameters
coefficientssequence of float

Polynomial coefficients in increasing polynomial order.

Examples

>>> import openturns as ot

Create a univariate polynomial from a list of coefficients:

>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P)
1 + 2 * X + 3 * X^2

Univariate polynomials are of course callable:

>>> print(P(1.0))
6.0

Addition, subtraction and multiplication of univariate polynomials:

>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> Q = ot.UniVariatePolynomial([1.0, 2.0])
>>> print('(%s) + (%s) = %s' % (P, Q, P + Q))
(1 + 2 * X + 3 * X^2) + (1 + 2 * X) = 2 + 4 * X + 3 * X^2
>>> print('(%s) - (%s) = %s' % (P, Q, P - Q))
(1 + 2 * X + 3 * X^2) - (1 + 2 * X) = 3 * X^2
>>> print('(%s) * (%s) = %s' % (P, Q, P * Q))
(1 + 2 * X + 3 * X^2) * (1 + 2 * X) = 1 + 4 * X + 7 * X^2 + 6 * X^3

Methods

__call__(self, \*args)

Call self as a function.

derivate(self)

Build the first-order derivative polynomial.

draw(self, xMin, xMax, pointNumber)

Draw the function.

getClassName(self)

Accessor to the object’s name.

getCoefficients(self)

Accessor to the polynomials’s coefficients.

getDegree(self)

Accessor to the polynomials’s degree.

getId(self)

Accessor to the object’s id.

getImplementation(self)

Accessor to the underlying implementation.

getName(self)

Accessor to the object’s name.

getRoots(self)

Compute the roots of the polynomial.

gradient(self, x)

Compute the gradient at point x.

hessian(self, x)

Compute the hessian at point x.

incrementDegree(self[, degree])

Multiply the polynomial by x^k.

setCoefficients(self, coefficients)

Accessor to the polynomials’s coefficients.

setName(self, name)

Accessor to the object’s name.
__init__(self, \*args)

Initialize self. See help(type(self)) for accurate signature.

derivate(self)

Build the first-order derivative polynomial.

Returns
derivated_polynomialUnivariate

The first-order derivated polynomial.

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.derivate())
2 + 6 * X
draw(self, xMin, xMax, pointNumber)

Draw the function.

Parameters
x_minfloat, optional

The starting value that is used for meshing the x-axis.

x_maxfloat, optional, x_{\max} > x_{\min}

The ending value that is used for meshing the x-axis.

n_pointsint, optional

The number of points that is used for meshing the x-axis.

Examples

>>> import openturns as ot
>>> from openturns.viewer import View
>>> f = ot.UniVariatePolynomial([1.0, 2.0, -3.0, 5.0])
>>> View(f.draw(-10.0, 10.0, 100)).show()
getClassName(self)

Accessor to the object’s name.

Returns
class_namestr

The object class name (object.__class__.__name__).

getCoefficients(self)

Accessor to the polynomials’s coefficients.

Returns
coefficientsPoint

Polynomial coefficients in increasing polynomial order.

See also

setCoefficients

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.getCoefficients())
[1,2,3]
getDegree(self)

Accessor to the polynomials’s degree.

Returns
degreeint

Polynomial’s degree.

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.getDegree())
2
getId(self)

Accessor to the object’s id.

Returns
idint

Internal unique identifier.

getImplementation(self)

Accessor to the underlying implementation.

Returns
implImplementation

The implementation class.

getName(self)

Accessor to the object’s name.

Returns
namestr

The name of the object.

getRoots(self)

Compute the roots of the polynomial.

Returns
rootslist of complex values

Polynomial’s roots.

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.getRoots())
[(-0.333333,0.471405),(-0.333333,-0.471405)]
gradient(self, x)

Compute the gradient at point x.

Returns
gradientfloat

The value of the function’s first-order derivative at point x.

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.gradient(1.0))
8.0
hessian(self, x)

Compute the hessian at point x.

Parameters
xfloat

Input value.

Returns
hessianfloat

The value of the function’s second-order derivative at point x.

incrementDegree(self, degree=1)

Multiply the polynomial by x^k.

Parameters
degreeint, optional

The incremented degree k. Default uses k = 1.

Returns
incremented_degree_polynomialUniVariatePolynomial

Polynomial with incremented degree.

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> print(P.incrementDegree())
X + 2 * X^2 + 3 * X^3
>>> print(P.incrementDegree(2))
X^2 + 2 * X^3 + 3 * X^4
setCoefficients(self, coefficients)

Accessor to the polynomials’s coefficients.

Parameters
coefficientssequence of float

Polynomial coefficients in increasing polynomial order.

See also

getCoefficients

Examples

>>> import openturns as ot
>>> P = ot.UniVariatePolynomial([1.0, 2.0, 3.0])
>>> P.setCoefficients([4.0, 2.0, 1.0])
>>> print(P)
4 + 2 * X + X^2
setName(self, name)

Accessor to the object’s name.

Parameters
namestr

The name of the object.