[Numpy-discussion] addition, multiplication of a polynomial and np.{float, int}

Charles R Harris charlesr.harris@gmail....
Tue Mar 6 15:19:29 CST 2012


On Tue, Mar 6, 2012 at 2:03 PM, Denis Laxalde <denis.laxalde@mcgill.ca>wrote:

> Hi,
>
>    >>> np.__version__
>    '1.7.0.dev-7c07089'
>    >>> p = np.poly1d([1,1])
>    >>> p + 1.0
>    poly1d([ 1.,  2.])
>    >>> p + np.float64(1)
>    poly1d([ 1.,  2.])
>    >>> np.float64(1.0) + p
>    array([ 2.,  2.])
>    >>> np.int64(1) + p
>    array([2, 2])
>    >>> np.int(1) + p
>    poly1d([1, 2])
>    >>> np.int64(1)*p
>    array([1, 1])
>
> What's happening here? I'd expect operations with polynomials would
> return a polynomial.
>

Use polynomial.Polynomial and you won't have this problem.

Chuck
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