I've found a couple of issues with differentiation in InfinitePolynomialRing
(ISSUE #1) Differentiation fails in InfinitePolynomialRing(QQ), e.g. the following code R.<x> = InfinitePolynomialRing(QQ) f = x[0] + x[1] derivative(f,x[1]) gives an error TypeError: Argument 'var' has incorrect type (expected sage.rings.polynomial.multi_polynomial_libsingular.MPolynomial_libsingular, got InfinitePolynomial_dense) However, if we replace QQ with something more sophisticated, differentiation starts suddenly work: K.<u> = PolynomialRing(QQ) R.<x> = InfinitePolynomialRing(K) f = x[0] + x[1] derivative(f,x[1]) gives 1 as expected. (ISSUE #2) Slightly modifying the second example above: K.<u> = PolynomialRing(QQ) R.<x> = InfinitePolynomialRing(K) f = x[0] + x[1] derivative(f,x[2]) we get an error ValueError: cannot differentiate with respect to x_2 However, if we try to execute the same 'derivative(f,x[2])' command again in the same Sage session, it will succeed. So, it appears that if we differentiate with respect to a new variable, which was not accessed before, then differentiation would fail. I hope this is not an intended behavior and can be easily fixed. Thanks, Max -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/fff3d8a2-9cc5-415f-aed1-8c4e90e14420n%40googlegroups.com.
