i found that >>>sqrt(4.41) 2.10000000 i guess we have no problem with this .
the problem we have is with .is_rational (rational checking function) so when sqrt(4.41).is_rational is called , we should call sqrt(nsimplify(4.41,rational=True)).is_rational which gives True in sympy ... also sqrt(4.41).is_rational would be more user friendly term than sqrt(nsimplify(4.41,rational=True)).is_rational On Sun, Mar 4, 2012 at 10:24 AM, prateek papriwal <papriwalprat...@gmail.com > wrote: > so somehow we need to merge nsimplify() method into sqrt() method . > > in that case when we call sqrt(4.41) > > automatically sqrt(nsimplify(4.41,rational=True)) will be called . > > > > > On Sun, Mar 4, 2012 at 10:07 AM, Aaron Meurer <asmeu...@gmail.com> wrote: > >> Exactly. This happens automatically for rational numbers, so that if >> the number is a perfect square, then they will be reduced (indeed, it >> will reduce any perfect square factors if the number is not too big). >> sqrt() of a Float will just give you another Float, so if you want to >> test that, you have to convert it to a Rational first. Normally, I >> would suggest calling Rational on it to do that, but that won't work >> because of issue http://code.google.com/p/sympy/issues/detail?id=2950. >> >> So instead, you should use nsimplify(rational=True), like >> >> In [58]: nsimplify(4.41, rational=True) >> Out[58]: >> 441 >> ─── >> 100 >> >> In [59]: sqrt(nsimplify(4.41, rational=True)) >> Out[59]: >> 21 >> ── >> 10 >> >> Aaron Meurer >> >> On Sat, Mar 3, 2012 at 9:09 PM, prateek papriwal >> <papriwalprat...@gmail.com> wrote: >> > we can do the following thing (talking about square roots) >> > >> > For integer inputs, only the square roots of the square numbers are >> > rationals. So our problem boils down to find if our number is a square >> > number . in this way sqrt(3) can be checked . >> > If we have rational numbers as inputs (that is, a number given as the >> ratio >> > between two integer numbers), check that both divisor and dividend are >> > perfect squares. in this way 4.41 can be checked . >> > >> > Finally we know that any finite floating point number is a rational >> number >> > .. >> > On Sun, Mar 4, 2012 at 5:05 AM, Aaron Meurer <asmeu...@gmail.com> >> wrote: >> >> >> >> On Sat, Mar 3, 2012 at 12:17 PM, Sergiu Ivanov >> >> <unlimitedscol...@gmail.com> wrote: >> >> > On Sat, Mar 3, 2012 at 6:29 PM, prateek papriwal >> >> > <papriwalprat...@gmail.com> wrote: >> >> >> yes u were right i had an old version 6.7 , now i have a new version >> >> >> which >> >> >> gives "NONE" for >> >> >> >> >> >>>>>sqrt(3).is_rational >> >> >> and >> >> >> >> >> >>>>>sqrt(3).is_irrational >> >> >> >> >> >> this need to be corrected >> >> > >> >> > Yes, this would be highly desired, but, as Aaron has said, there is >> no >> >> > simple general way to check the rationality of an expression. >> >> > >> >> > Could you please describe what you are trying to achieve? If you can >> >> > narrow down your problem sufficiently well, you may be able to devise >> >> > an ad-hoc way to check the rationality of an expression in your >> >> > domain. >> >> > >> >> > Sergiu >> >> >> >> Problems only arise if you have transcendental numbers, or if you have >> >> symbolic expressions with some assumptions on them. If you are >> >> dealing with a non-symbolic algebraic number, it is always possible to >> >> tell if it's rational or not. One way is to use minpoly() and see if >> >> the minimal polynomial is linear or not. We don't currently do this >> >> because minpoly() is too slow for non-trivial algebraic numbers (if I >> >> remember correctly). >> >> >> >> Aaron Meurer >> >> >> >> -- >> >> You received this message because you are subscribed to the Google >> Groups >> >> "sympy" group. >> >> To post to this group, send email to sympy@googlegroups.com. >> >> To unsubscribe from this group, send email to >> >> sympy+unsubscr...@googlegroups.com. >> >> For more options, visit this group at >> >> http://groups.google.com/group/sympy?hl=en. >> >> >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "sympy" group. >> > To post to this group, send email to sympy@googlegroups.com. >> > To unsubscribe from this group, send email to >> > sympy+unsubscr...@googlegroups.com. >> > For more options, visit this group at >> > http://groups.google.com/group/sympy?hl=en. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To post to this group, send email to sympy@googlegroups.com. >> To unsubscribe from this group, send email to >> sympy+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/sympy?hl=en. >> >> > -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
