`numpy.polynomial.legendre:legmulx`

Signature

def legmulx(c)

Multiply a Legendre series by x.

Multiply the Legendre series c by x, where x is the independent variable.

c : array_like: 1-D array of Legendre series coefficients ordered from low to high.

The multiplication uses the recursion relationship for Legendre polynomials in the form

x P_{i} (x) = ((i + 1) * P_{i + 1} (x) + i * P_{i - 1} (x)) / (2 i + 1)

from numpy.polynomial import legendre as L

✓

L.legmulx([1,2,3])

✗

array([0.6667, 2.2   , 1.3333, 1.8   ])