Re: Horner scheme function ?
- To: mathgroup at smc.vnet.net
- Subject: [mg4539] Re: [mg4414] Horner scheme function ?
- From: Allan Hayes <hay at haystack.demon.co.uk>
- Date: Wed, 7 Aug 1996 04:17:45 -0400
- Sender: owner-wri-mathgroup at wolfram.com
kraft at emma.bauwesen.uni-dortmund.de (Manfred Krafczyk)
[mg4414] Horner scheme function ?
writes
>does anybody know where I can find a Mathematica
>function that returns the Horner representation
> of a polynomial ... ?
Manfred:
HornerForm::usage =
"HornerForm[poly,x] give the HornerForm for the polynomial
poly in x"]
HornerForm[poly_,x_] :=
Fold[(#1 x + #2 )&,0, Reverse[CoefficientList[poly,x]]]
Check:
p[x_] = Sum[ Random[Integer,{-9,9}] x^n, {n,0,5}]
2 3 4 5
-5 - 9 x - x + 4 x - 7 x - 8 x
HornerForm[p[x],x]
-5 + x (-9 + x (-1 + x (4 + (-7 - 8 x) x)))
HornerForm[x^3 + x^4,x]
3
x (1 + x)
Allan Hayes
hay at haystack.demon.co.uk
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