coefficient() with composite variable

Say I have something like this:

var('a','b','c')
test=b*a + c*a + 3*a + b + c

I can find that the coefficient of 'a' is (b+c+3) using:

test.coefficient(a,1)

However, I am interested in find the coefficient of $ab$ (which in this case would just be $1$). I tried

test.coefficient(a*b,1)

but it just returns zero. Is something like this possible?

1 Answer

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You can work in a polynomial ring.

sage: R.<a,b,c> = PolynomialRing(QQ)
sage: p = b * a + c * a + 3 * a + b + c
sage: p.coefficient(a*b)
1

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Asked: 2013-04-15 10:45:57 +0100

Seen: 237 times

Last updated: Apr 15 '13