Hi, On 11 July 2013 11:14, Thilina Rathnayake <[email protected]> wrote:
> Hi, > > I implemented the extended_euclid() in Diophantine module without knowing > that > gcdex() existed. However, Chris pointed out that extended_euclid() is > much faster. > Take a look at > here<https://github.com/sympy/sympy/pull/2168#discussion-diff-4672557>. > He suggested to rename extended_euclid() to igcdex(). > btw. Even if you don't know if a function exists or if it exists what is it's name, it's not that hard learn it. For example, the following simple query (could be extended to give broader results, if necessary) with git grep gives quite a lot of results: $ git grep -i "extended\s\+euclid" sympy/integrals/risch.py: Extended Euclidean Algorithm, Diophantine version. sympy/integrals/risch.py: # Extended Euclidean Algorithm (Diophantine Version) pg. 13 sympy/polys/euclidtools.py: Half extended Euclidean algorithm in `F[x]`. sympy/polys/euclidtools.py: Half extended Euclidean algorithm in `F[X]`. sympy/polys/euclidtools.py: Extended Euclidean algorithm in `F[x]`. sympy/polys/euclidtools.py: Extended Euclidean algorithm in `F[X]`. sympy/polys/galoistools.py: Extended Euclidean Algorithm in ``GF(p)[x]``. sympy/polys/galoistools.py: in ``GF(11)[x]``. Application of Extended Euclidean Algorithm gives:: sympy/polys/polyclasses.py: """Half extended Euclidean algorithm, if univariate. """ sympy/polys/polyclasses.py: """Extended Euclidean algorithm, if univariate. """ sympy/polys/polytools.py: Half extended Euclidean algorithm of ``f`` and ``g``. sympy/polys/polytools.py: Extended Euclidean algorithm of ``f`` and ``g``. sympy/polys/polytools.py: Half extended Euclidean algorithm of ``f`` and ``g``. sympy/polys/polytools.py: Extended Euclidean algorithm of ``f`` and ``g``. It doesn't give you igcdex() directly, but then you can check those results and learn that the name is gcdex() and either grep again for "def gcdex" or follow implementation tree to igcdex() (gcdex() -> PythonIntegerRing.gcdex() -> igcdex()). > I also feel that when we are dealing with integers, i.e when using igcd()we > should > allow inputting more than two numbers at a time. It doesn't break the API, > does it? > > Regards, > Thilina > > > On Thu, Jul 11, 2013 at 2:12 PM, Mateusz Paprocki <[email protected]>wrote: > >> Hi, >> >> On 11 July 2013 10:17, Stephen Loo <[email protected]> wrote: >> >>> Hi all, >>> >>> I found that there are many different kind of gcd in sympy different >>> module, such as >>> >>> sympy.core.numbers.igcd >>> sympy.polys.polytools.gcd >>> sympy.polys.polytools.gcdex >>> sympy.polys.polytools.gcd_list >>> sympy.polys.polytools.half_gcdex >>> >>> And the new one >>> sympy.solvers.diophantine.extended_euclid >>> >>> They calculate integer gcd or polynomial gcd. I suggest to make single >>> public function call, like gamma, put in integer argument and return >>> integer, put in polynomial argument and return polynomial. And gcd function >>> should not limit to 2 integer only, for example, gcd(10, 15, 20) = 5 >>> >>> Any idea? Any suggestion? >>> >> >> First of all, functions gcdex() and half_gcdex() don't count because they >> implement extended Euclidean algorithm. I didn't know about >> extended_euclid(). It seems redundant. igcd() is a specialized function >> that works only with integers and is needed internally to reduce overhead >> that gcd() function has. The function you would like to have is gcd(). It >> works with numbers, polynomials and whatever that has a gcd() method. It >> either takes two arguments (plus symbols and options in polynomial case) or >> one iterable (plus symbols and options in polynomial case). The iterable >> case is equivalent to calling gcd_list() explicitly (that's why there is >> gcd_list()). Currently it isn't possible to support gcd(1, 2, 3, 4, 5) >> syntax, because that effectively means (in the current API) compute GCD of >> 1 and 2 which are polynomials in 3, 4, 5 (treated as symbols) in the >> default coefficient domain (which is integer ring). In the integer case >> this limitation could be relaxed easily, but then the API would be >> inconsistent, because gcd(x, y, z) would still mean GCD of polynomials x >> and y in z (x*z**0, y*z**0) (over ZZ[x, y]). >> >> >>> Thanks. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "sympy" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/sympy. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >>> >>> >> >> Mateusz >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/sympy. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> >> > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > For more options, visit https://groups.google.com/groups/opt_out. > > > Mateusz -- You received this message because you are subscribed to the Google Groups "sympy" group. 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