# numpy.polymul

`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.

### 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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