Christian Kristukat <ckkart@hoc.net> writes:

Ryan Krauss wrote:

...

Is there an easy way to test for the equality of two poly1d objects?

I have the following problem: In [36]: p1 Out[36]: poly1d([ 6.66666667, 0. , -49. ])

In [37]: p2 Out[37]: poly1d([ 6.66666667, 0. , -49. ])

In [38]: p1==p2 Out[38]: False

In [39]: (p1.coeffs==p2.coeffs).all() Out[39]: True

It seems like == is only testing if they are the same object. I am trying to write a class for transfer functions which model a system as a numerator and denominator poly1d. When I multiply or divide them I need to check if the numerator and denominators cancel exactly.

Hi Ryan, you could subclass poly1d and define the special method __eq__ to which is called in situations lika a==b:

In [3]: class p(poly1d): ...: def __eq__(self,other): ...: return (self.coeffs==other.coeffs).all() ...: ...:

In [4]: p1 = p([ 6.66666667, 0. , -49. ])

In [5]: p2 = p([ 6.66666667, 0. , -49. ])

In [6]: p1 == p2 Out[6]: True

I've added __eq__ and __ne__ methods to the poly1d class in svn. -- |>|\/|< /--------------------------------------------------------------------------\ |David M. Cooke http://arbutus.physics.mcmaster.ca/dmc/ |cookedm@physics.mcmaster.ca