Polynomial operations with np.poly in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does np.poly do in NumPy?

np.poly returns the coefficients of a polynomial whose roots are given. It helps create a polynomial from its roots.

beginner

How are polynomial coefficients ordered in NumPy arrays?

Coefficients are ordered from the highest degree term to the constant term. For example, [1, -3, 2] means 1*x^2 - 3*x + 2.

intermediate

How to multiply two polynomials using NumPy?

Use np.polymul(p1, p2) where p1 and p2 are arrays of coefficients. It returns coefficients of the product polynomial.

beginner

What function helps find the roots of a polynomial given its coefficients?

np.roots(coefficients) returns the roots of the polynomial defined by the given coefficients.

intermediate

How to add two polynomials in NumPy?

Pad the shorter coefficient array with zeros on the left, then add element-wise. NumPy does not have a direct add function for polynomials.

What does np.poly([1, 2, 3]) return?

A Coefficients of polynomial with roots 1, 2, 3

B Roots of polynomial with coefficients 1, 2, 3

C Polynomial evaluated at points 1, 2, 3

D Derivative of polynomial with roots 1, 2, 3

np.poly returns coefficients of a polynomial with the given roots.

How are polynomial coefficients ordered in NumPy arrays?

A From highest degree to constant term

B Random order

C From constant term to highest degree

D From lowest degree to highest degree

NumPy orders coefficients from highest degree term to constant term.

Which function multiplies two polynomials in NumPy?

A np.polyadd

B np.polymul

C np.polydiv

D np.polyroots

np.polymul multiplies two polynomials.

What does np.roots([1, -3, 2]) return?

A Integral of polynomial

B Coefficients of polynomial

C Derivative of polynomial

D Roots of polynomial x² - 3x + 2

np.roots finds roots of the polynomial with given coefficients.

How to add two polynomials in NumPy?

A Use np.polyadd

B Use np.polymul

C Pad shorter array with zeros and add element-wise

D Use np.polydiv

NumPy does not have direct add function; pad and add element-wise.

Explain how to create a polynomial from its roots using NumPy.

Think about how roots relate to polynomial factors.

Describe how to multiply two polynomials represented by coefficient arrays in NumPy.

Multiplying polynomials is like multiplying their coefficient arrays.