Chris wrote:
sin(pi*0.5) is what I expected, but I expected to get 0 for sin(pi).
Computers in general, and Python too, usually use floating point
arithmetic in which all numbers are approximated by rational numbers of
a particular form (see http://en.wikipedia.org/wiki/Floating_point for
Dave Benjamin wrote:
[EMAIL PROTECTED] wrote:
Now suppose I set expression2 = Sum([a,-a]) and Sum.simplify()
recognises that the two terms cancel and the Sum has value 0.
Can I make expression2.simplify() transform expression2 from an
instance of Sum to an instance of Number(0) **in
Hello comp.lang.py,
Can you help me with ideas for the following (somewhat newbie) OO
design question in Python? Note, I'm using psuedo-code, not actual
Python for the examples!
Background:
---
I need to represent a small variety of mathematical constructs
symbolically using Python
Bruno Desthuilliers wrote:
You've already got the technical answer. About a possible design
flaw,
it would seem to me that restricting the join() operation on specific
subclasses breaks the LSP. OTOH, Python being dynamically typed,
inheritence is merely an implementation detail, so that may
Hi all,
Sorry if the post's title is confusing... I'll explain:
I have a class, called A say, and N1 subclasses of A, called
A1, A2, A3, ..., AN say.
Instances of each subclass can sensibly be joined together with other
instances of the *same subclass*. The syntax of the join method is
Assuming that A is a new-style class then if they have to be
exactly the same type compare the types
Ah-ha! I didn't know that.
if the 'other' value can be a subclass of self:
def join(self, other):
if not isinstance(other, type(self)):
raise whatever
Simple and neat!
If A
