Birational Transformation

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guissmo
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How do I apply a birational transformation x --> 1/x, then clear the denominators. Is there a way I could do that in SAGE?

x, y = QQ['x,y'].gens()
C = Curve(x^2+y^2)
# the code I'm looking for here

$x^2 + y^2 \mapsto 1/x^2 + y^2 \mapsto 1/x^2 + x^2y^2/x^2 \mapsto 1 + x^2y^2$

1 Answer

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Perhaps

sage: x, y = QQ['x,y'].gens()
sage: P = x^2 + y^2
sage: Q = P(1/x, y)
sage: Q.denominator() * Q
x^2*y^2 + 1

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Asked: 11 years ago

Seen: 365 times

Last updated: May 28 '13