numpy.polynomial.legendre.legsub(c1, c2)[source]

Subtract one Legendre series from another.

Returns the difference of two Legendre series c1 - c2. The sequences of coefficients are from lowest order term to highest, i.e., [1,2,3] represents the series P_0 + 2*P_1 + 3*P_2.

Parameters :

c1, c2 : array_like

1-D arrays of Legendre series coefficients ordered from low to high.

Returns :

out : ndarray

Of Legendre series coefficients representing their difference.

See also

legadd, legmul, legdiv, legpow


Unlike multiplication, division, etc., the difference of two Legendre series is a Legendre series (without having to “reproject” the result onto the basis set) so subtraction, just like that of “standard” polynomials, is simply “component-wise.”


>>> from numpy.polynomial import legendre as L
>>> c1 = (1,2,3)
>>> c2 = (3,2,1)
>>> L.legsub(c1,c2)
array([-2.,  0.,  2.])
>>> L.legsub(c2,c1) # -C.legsub(c1,c2)
array([ 2.,  0., -2.])

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