There was a thread on multiple return values coming from Magma, since renamed to "Integer points on conics"
William pointed out that one can access the multiple return values using nvals: x = magma.XGCD(15, 10) x,y,z = magma.XGCD(15, 10, nvals = 3) The first returns an integer, while the second returns a tuple. Q1: Is this an acceptable general construction for Python and/or SAGE, namely to return a different type depending on the values passed into it? Is it acceptable when it is controlled by nvals in exactly this way? As William pointed out, very different algorithms can be called depending on the number of arguments requested in Magma. The following is an example: sage: E = magma.EllipticCurve([1,3]) sage: magma.IsIsomorphic(E,E) true sage: bool, phi = magma.IsIsomorphic(E,E,nvals=2) sage: phi Elliptic curve isomorphism from: Elliptic Curve defined by y^2 = x^3 + x + 3 over Rational Field to Elliptic Curve defined by y^2 = x^3 + x + 3 over Rational Field Taking (x : y : 1) to (x : y : 1) Currently in SAGE we have: sage: E = EllipticCurve([1,3]) sage: E.is_isomorphic(E) True Q2: Would the following be acceptable way of implementing equivalent functionality in SAGE?: sage: bool, phi = E.is_isomorphic(E, nvals=2) Note that often (in many concexts) it more expensive to return an isomorphism, but only slightly more so compared with recomputing the isomorphism test. If the answer to my question is "no, it not acceptable SAGE/Python syntax", then how should we implement this functionality? One possibility is: sage: phi = E1.isomorphism(E2) and to trap an error if is_isomorphic returns false. Is this a better? --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
