[Numpy-discussion] polynomial with negative exponents

LASAGNA DAVIDE davide.lasagna at polito.it
Mon Dec 12 09:04:56 EST 2011


I have written a class for polynomials with negative 
exponents like:

p(x) = a0 + a1*x**-1 + ... + an*x**-n

The code is this one:

class NegativeExpPolynomial( object ):
      def __init__ ( self, coeffs ):
          self.coeffs = np.array( coeffs )

      def __call__( self, x ):
          return sum( (c*x**(-i) for i, c in enumerate( 
self.coeffs ) ) )

where coeffs = [a0, a1, ..., an].

I find that the way i evaluate the polynomial is kind of 
*slow*, especially for polynomial with order larger than 
~200 and for arrays x large enough.

Do you have suggestions on how to speed up this code?


Davide Lasagna

Phd Student
Dipartimento di Ingegneria Aeronautica a Spaziale
Politecnico di Torino, Italy
tel: 011/0906871
e-mail: davide.lasagna at polito.it; lasagnadavide at gmail.com

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