True. But the conditional
sage: A=x+x^2
sage: if A.operator()=="<built-in function add>":
sage: print "Y"
sage: else:
sage: print "N"
fails to give "Y". How can I patch this up?
On May 15, 1:57 am, Jason Grout <jason-s...@creativetrax.com> wrote:
> On 5/14/11 8:32 PM, MathLynx wrote:
>
> > How can I use Sage to determine if an expression is a sum - i.e. if
> > the last operation performed is either addition or subtraction?
>
> > Thus, I would like to identify "a*(b+c)" as a product but "a*b+a*c" as
> > a sum.
>
> > It would be nice to also identify the number of summands in an
> > addition - or multiplicands in a product - i.e. "a*b+a*c" should be a
> > sum with two summands, as opposed to "a*b+a*c+a*d" having three
> > summands.
>
> You can use operands() and operator() to do these things:
>
> sage: var('a,b,c,d')
> (a, b, c, d)
> sage: f=a*b+a*c+a*d
> sage: f.operands()
> [a*b, a*c, a*d]
> sage: f.operator()
> <built-in function add>
> sage: g=a*(b+c)
> sage: g.operands()
> [b + c, a]
> sage: g.operator()
> <built-in function mul>
>
> Jason
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