2017-09-06 00:35:45 -0500 received badge ● Popular Question (source) 2014-11-18 05:26:02 -0500 received badge ● Nice Question (source) 2014-11-13 07:14:22 -0500 commented answer Comparing numbers in an algebraic field Thanks Thierry. Actually what is even stranger is that floor(x-y)>=0 works well in place of x>=y. The problem with AA is that there seem to be some memory leaks :-/ 2014-11-12 13:25:40 -0500 asked a question Comparing numbers in an algebraic field I get a very strange results from comparison of number in an algebraic field, see the example: version() X = polygen(ZZ) f = X^3 - 2*X^2 - 2*X - 2 Qb. = QQ.extension(f, embedding=3) b.N() # b is positive 0 < b # gives False; why? 0 < 1 # gives True; fine Qb(0) < Qb(1) # gives False; WTF?  sage: version() 'Sage Version 6.1.1, Release Date: 2014-02-04' sage: X = polygen(ZZ) sage: f = X^3 - 2*X^2 - 2*X - 2 sage: Qb. = QQ.extension(f, embedding=3) sage: sage: b.N() # b is positive 2.91963956583942 sage: 0 < b # gives False; why? False sage: 0 < 1 # gives True; fine True sage: Qb(0) < Qb(1) # gives False; WTF? False sage:  Can I do something to obtain the correct results of comparison, or is using the flawed .N() the only option? 2014-06-29 11:53:35 -0500 received badge ● Notable Question (source) 2014-06-29 11:53:35 -0500 received badge ● Popular Question (source) 2014-06-29 06:38:06 -0500 received badge ● Popular Question (source) 2014-06-29 06:38:06 -0500 received badge ● Notable Question (source) 2014-06-29 06:38:06 -0500 received badge ● Famous Question (source) 2014-04-17 02:26:42 -0500 commented question QQ.extension() with embedding: incorrect modulus Thanks @Francis for pointing it out, I wasn't aware that this is the issue! And you're welcome, Thierry :) 2014-04-11 00:38:29 -0500 received badge ● Editor (source) 2014-04-11 00:34:40 -0500 asked a question QQ.extension() with embedding: incorrect modulus Minimal Example: print version() # get the version ZX.=ZZ[] # polynomials in X f=X^3-X-1 # minimal polynomial of minimal Pisot roots=f.complex_roots() # its roots root_beta=roots[0] # the real root is first print 'A:', root_beta # verify we got the real root Qb. = QQ.extension(f, embedding=root_beta) # make an extension float_beta = CC(ext_beta) # convert to float print 'B:', float_beta.abs() print 'C:', ext_beta.abs() # why B != C ??? print 'D:', roots[1].abs() # it turns out that ext_beta.abs() gives the modulus of another root of f !!!  Output: Sage Version 6.1.1, Release Date: 2014-02-04 A: 1.32471795724475 B: 1.32471795724475 C: 0.868836961832709 D: 0.868836961832709  The problem is that ext_beta.abs() != CC(ext_beta).abs() for ext_beta the generator of an algebraic extension, which just doesn't sound right (and arises some problems of course). I want to work in precise arithmetics, therefore I need to apply abs() without conversion to floats. Is there any way how to achieve this? 2014-04-10 14:01:10 -0500 received badge ● Student (source) 2013-12-31 14:04:48 -0500 received badge ● Scholar (source) 2013-12-31 14:04:48 -0500 marked best answer Running sage --testall in parallel It is possible to run the doctests in parallel, see this page. In your case, you can use the -tp 4 --all option. 2013-12-31 14:04:46 -0500 received badge ● Supporter (source) 2013-12-29 04:07:33 -0500 asked a question Running sage --testall in parallel Hello there! After an install of sage from binaries (Fedora20), I ran sage --testall. However, it takes quite a lot of time (3000s). I have 4 processors and running this in parallel would shorten it significantly (and it should be easily possible to run the tests in parallel). Therefore my question: Can I run the tests in parallel? And how?