numpy.polymul(a1, a2)

The `numpy.polymul`

function finds the product (multiplication) of two polynomials `a1`

and `a2`

. As an input, use either poly1d objects or one-dimensional sequences of polynomial coefficients. If you use the latter, arange this polynomial sequence naturally from highest to lowest degree.

Arguments | Type | Description |
---|---|---|

a1, a2 | array_like or poly1d object | The input polynomials to be multiplied |

Return Value | ndarray or poly1d object | The polynomial resulting from the multiplication of the inputs. If either inputs is a poly1d object, then the output is also a poly1d object. Otherwise, it is a 1D array of polynomial coefficients from highest to lowest degree. |

### Examples

import numpy as np print(np.polymul([1, 2, 3], [2, 3, 4])) # [ 2 7 16 17 12]

You can also use poly1d objects:

import numpy as np p1 = np.poly1d([1, 2, 3]) p2 = np.poly1d([2, 3, 4]) print(p1) print(p2) print(np.polymul(p1, p2)) ''' 2 1 x + 2 x + 3 2 2 x + 3 x + 4 4 3 2 2 x + 7 x + 16 x + 17 x + 12 '''

As you see the output looks much like a real polynomial if you use poly1d objects.

Any master coder has a “hands-on” mentality with a bias towards action. Try it yourself—play with the function in the following interactive code shell:

**Exercise**: Change the parameters of your polynomials. How does the output change? Guess and check!

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