2008/10/28 John Cremona <[EMAIL PROTECTED]>: > It should not be difficult to convert the power series over GF(p) to > pari. If you do > > sage: R.<x>=PowerSeriesRing(GF(5),"x") > sage: f = x^2+1 > > and then > > sage: f._pari_?? > > you will see the comment that converson of power series from Sage to > pari is currently only implemented over QQ and ZZ. And that > implementation is rather crude, as it goes via the string > representation. It would be better to be able to convert power series > over any ring which itself can be converted. >
This is now trac ticket #4376. > John Cremona > > 2008/10/28 salmanhb <[EMAIL PROTECTED]>: >> >> >> Hi, >> >> I've got a (truncated) matrix over a power series ring over a finite >> field that I want to convert to a GP matrix so that I can take its >> kernel. Since the matrix is truncated, it can be viewed as just being >> over a univariate polynomial ring. I want to take its kernel, but the >> echelon form over a univariate polynomial ring over a finite field is >> not yet implemented. I knew GP can do this, so I was going to send the >> matrix to GP and have GP compute the kernel. But if I send the matrix >> as a matrix over the power series ring, the coefficients are not sent >> as being over a finite field. On the other hand, if I redefine the >> matrix over the polynomial ring, the coefficients are treated as being >> over a finite field. I could reconstruct all of my matrices as being >> over the polynomial ring once I truncate my series, but that seems >> like a silly hack -- GP understands power series rings over a finite >> field, so the conversion shouldn't be a problem. I'm running SAGE >> v3.0.2. >> >> Thanks, >> Salman >> >> Here is the code and output: >> >> sage: R.<x>=PowerSeriesRing(GF(5),"x") >> sage: m=matrix(R,2,[2+x, 1+x, 2+3*x,1+2*x]) >> sage: m.kernel() >> --------------------------------------------------------------------------- >> NotImplementedError Traceback (most recent call >> last) >> >> /Users/salmanhb/Documents/work/research/computations/sage/<ipython >> console> in <module>() >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.left_kernel (sage/matrix/matrix2.c:7985) >> () >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.echelon_form (sage/matrix/matrix2.c: >> 15292)() >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.echelonize (sage/matrix/matrix2.c:15092) >> () >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix._echelonize_ring (sage/matrix/matrix2.c: >> 14807)() >> >> NotImplementedError: echelon form over Power Series Ring in x over >> Finite Field of size 5 not yet implemented >> sage: gp(m) >> [x + 2, x + 1; 3*x + 2, 2*x + 1] >> sage: R.<x>=PolynomialRing(GF(5),"x") >> sage: m=matrix(R,2,[2+x, 1+x, 2+3*x,1+2*x]) >> sage: m.kernel() >> --------------------------------------------------------------------------- >> NotImplementedError Traceback (most recent call >> last) >> >> /Users/salmanhb/Documents/work/research/computations/sage/<ipython >> console> in <module>() >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.left_kernel (sage/matrix/matrix2.c:7985) >> () >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.echelon_form (sage/matrix/matrix2.c: >> 15292)() >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix.echelonize (sage/matrix/matrix2.c:15092) >> () >> >> /Users/salmanhb/Documents/work/research/computations/sage/matrix2.pyx >> in sage.matrix.matrix2.Matrix._echelonize_ring (sage/matrix/matrix2.c: >> 14807)() >> >> NotImplementedError: echelon form over Univariate Polynomial Ring in x >> over Finite Field of size 5 not yet implemented >> sage: gp(m) >> [Mod(1, 5)*x + Mod(2, 5), Mod(1, 5)*x + Mod(1, 5); Mod(3, 5)*x + >> Mod(2, 5), Mod(2, 5)*x + Mod(1, 5)] >> >> >> > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@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-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
