[Edu-sig] Algebra + Python

[Brent Burley]

Kirby wrote:
> There may be a better way to write the factory function than
> I've shown below.  I'd like to see other solutions:
> 
>  >>> def makepoly(A,B,C):     
>         """
>         Build a polynomial function from coefficients
>         """
>         return eval("lambda x: %s*x**2 + %s*x + %s" % (A,B,C))

How about this?

class poly:
    def __init__(self, A, B, C):
        self.A, self.B, self.C = A, B, C
    def __call__(self, x):
        return self.A * x**2 + self.B * x + self.C

>>> f = poly(2,3,4)
>>> f(10)
234

Having to know about classes pushes you more into learning Python as a
programming language rather than just using Python as a math exploration
tool, but that could be a good thing.  You could even expand on the idea
by adding additional methods that relate to polynomials (deriv,
integral, roots, etc.):

class poly:
    ...
    def deriv(self, x):
        return 2*self.A*x + self.B

>>> f.deriv(2)
11


	Brent