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Sage Reference Manual: Elliptic and Plane Curves - Mirrors

Sage Reference Manual: Elliptic and Plane Curves - Mirrors

Sage Reference Manual: Elliptic and Plane Curves - Mirrors

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<strong>Sage</strong> <strong>Reference</strong> <strong>Manual</strong>: <strong>Elliptic</strong> <strong>and</strong> <strong>Plane</strong> <strong>Curves</strong>, Release 6.1.1(-24/25 : 7/25 : 1)sage: Conic(QQ, [1, 1, 1]).r<strong>and</strong>om_rational_point()Traceback (most recent call last):...ValueError: Conic Projective Conic Curve over Rational Field defined by x^2 + y^2 + z^2 hasrational_point(algorithm=’default’, read_cache=True)Return a point on self defined over the base field.Raises ValueError if no rational point exists.See self.has_rational_point for the algorithm used <strong>and</strong> for the use of the parametersalgorithm <strong>and</strong> read_cache.EXAMPLES:Examples over Qsage: R. = QQ[]sage: C = Conic(7*x^2 + 2*y*z + z^2)sage: C.rational_point()(0 : 1 : 0)sage: C = Conic(x^2 + 2*y^2 + z^2)sage: C.rational_point()Traceback (most recent call last):...ValueError: Conic Projective Conic Curve over Rational Field defined by x^2 + 2*y^2 + z^2 hasage: C = Conic(x^2 + y^2 + 7*z^2)sage: C.rational_point(algorithm = ’rnfisnorm’)Traceback (most recent call last):...ValueError: Conic Projective Conic Curve over Rational Field defined by x^2 + y^2 + 7*z^2 haExamples over number fieldssage: P. = QQ[]sage: L. = NumberField(x^3-5)sage: C = Conic(L, [3, 2, -5])sage: p = C.rational_point(algorithm = ’rnfisnorm’)sage: p# output is r<strong>and</strong>om(60*b^2 - 196*b + 161 : -120*b^2 - 6*b + 361 : 1)sage: C.defining_polynomial()(list(p))0sage: K. = QuadraticField(-1)sage: D = Conic(K, [3, 2, 5])sage: D.rational_point(algorithm = ’rnfisnorm’) # output is r<strong>and</strong>om(-3 : 4*i : 1)sage: L. = QuadraticField(2)sage: Conic(QQ, [1, 1, -3]).has_rational_point()Falsesage: E = Conic(L, [1, 1, -3])sage: E.rational_point()# output is r<strong>and</strong>om(-1 : -s : 1)Currently Magma is better at solving conics over number fields than <strong>Sage</strong>, so it helps to use the algorithm25

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