On Mar 10, 6:32 pm, Nathan Pinno <[EMAIL PROTECTED]> wrote: > On Mar 10, 12:10 pm, Mensanator <[EMAIL PROTECTED]> wrote: > > > > > > > On Mar 10, 12:48 am, Gabriel Genellina <[EMAIL PROTECTED]> wrote: > > > > On 10 mar, 02:08, Nathan Pinno <[EMAIL PROTECTED]> wrote: > > > > > How do I factor a number? > > > If factoring is actually what you want, the sympy module can do it. > > > >>> n = 85085**3 > > >>> print n > > 615969217989125 > > >>> import sympy > > >>> f = sympy.factorint(n) > > >>> f > > > [(5, 3), (7, 3), (11, 3), (13, 3), (17, 3)]>>> ff = [[i[0]]*i[1] for i in f] > > >>> ff > > > [[5, 5, 5], [7, 7, 7], [11, 11, 11], [13, 13, 13], [17, 17, 17]]>>> fff = > > sympy.flatten(ff) > > >>> fff > > > [5, 5, 5, 7, 7, 7, 11, 11, 11, 13, 13, 13, 17, 17, 17] > > > Provided that your needs are modest. It claims to be > > able to handle 10 digit factors, but it certainly can't > > handle numbers of this magnitude: > > > 50818429800343305993022114330311033271249313957919046352679206262204589342623811236647989889145173098650749 > > > As it takes a couple hours of run-time only to crash > > with an out of memory error. > > > If you need to handle something like that, you may want to > > get factor.exe which is part of the MIRACL library. The library > > is in C and doesn't have a Python interface, but you can run > > the .exe from Python and capture the output. > > > Keep in mind two things: factor.exe doesn't have consistent > > output making it more difficult to interpret the captured > > output. I re-compiled my copy of factor.exe to provide > > consistent output. > > > The other thing is that factor.exe sometimes gets confused > > claiming a number is composite that factor.exe is fully > > capable of factoring. Luckily this can be easily fixed in > > the Python program that calls it. > > > In the following example, if factor!.exe (my re-compiled > > version) returns any composites, I simply feed them back > > into the program until all are factored or determinened to > > be truly intractable. > > > Note the times. If you have serious factoring needs, the > > MIRACL solution is better than sympy. > > > ## ======================================== > > ## Phase 1 > > ## ['COMPOSITE_FACTOR', > > '50818429800343305993022114330311033271249313957919046352679206262204589342623811236647989889145173098650749'] > > ## > > ## ['PRIME_FACTOR', '37'] > > ## ['PRIME_FACTOR', '43'] > > ## ['PRIME_FACTOR', '167'] > > ## ['COMPOSITE_FACTOR', '507787751'] > > ## ['PRIME_FACTOR', '69847'] > > ## ['PRIME_FACTOR', '30697'] > > ## ['PRIME_FACTOR', '89017'] > > ## ['PRIME_FACTOR', '3478697'] > > ## ['PRIME_FACTOR', '434593'] > > ## ['PRIME_FACTOR', '49998841'] > > ## ['PRIME_FACTOR', '161610704597143'] > > ## ['PRIME_FACTOR', '14064370273'] > > ## ['COMPOSITE_FACTOR', '963039394703598565337297'] > > ## ['PRIME_FACTOR', '11927295803'] > > ## > > ## 0.860000133514 seconds > > ## ======================================== > > ## Phase 2 > > ## ['COMPOSITE_FACTOR', '507787751'] > > ## > > ## ['PRIME_FACTOR', '29819'] > > ## ['PRIME_FACTOR', '17029'] > > ## > > ## 0.0780000686646 seconds > > ## ======================================== > > ## Phase 3 > > ## ['COMPOSITE_FACTOR', '963039394703598565337297'] > > ## > > ## ['PRIME_FACTOR', '518069464441'] > > ## ['PRIME_FACTOR', '1858900129817'] > > ## > > ## 0.0469999313354 seconds > > ## ======================================== > > ## > > ## Factoring complete > > ## > > ## PRIME_FACTOR 37 > > ## PRIME_FACTOR 43 > > ## PRIME_FACTOR 167 > > ## PRIME_FACTOR 17029 > > ## PRIME_FACTOR 29819 > > ## PRIME_FACTOR 30697 > > ## PRIME_FACTOR 69847 > > ## PRIME_FACTOR 89017 > > ## PRIME_FACTOR 434593 > > ## PRIME_FACTOR 3478697 > > ## PRIME_FACTOR 49998841 > > ## PRIME_FACTOR 11927295803 > > ## PRIME_FACTOR 14064370273 > > ## PRIME_FACTOR 518069464441 > > ## PRIME_FACTOR 1858900129817 > > ## PRIME_FACTOR 161610704597143 > > ## > > ## ======================================== > > > > I mean how do I translate x! into proper > > > > Python code, so that it will always do the correct math? > > > > Do you want to compute x! (factorial of x)? That is, you want a > > > program that given a 4, returns 24? > > > Think how would you compute it by hand and try to write the same thing > > > using Python instructions. > > > > If you come with a program and have a specific problem someone here > > > will be able to help you, but don't expect your homework to be done > > > for free... > > > > -- > > > Gabriel Genellina > > Thanks on the factoring bit, but I did mean factorial, not factoring. > How do I code that correctly, so that I can figure the following > equation out: cos(Pi * (z-1)! / z). Python returns a invalid syntax > error and highlight the !.
Because Python doesn't support the factorial operator. > So it would be nice to find a way to solve > such a problem. Instead of using MIRACL which doesn't have a Python interface, you could instaed get the GMP library which DOES have a Python interface (Google for gmpy, make sure to get the version that matches your Python version). Then you can do gmpy.fac(z-1) to get the factorial. or >>> import math >>> import gmpy >>> a = math.cos(gmpy.pi(0)*gmpy.fac(4-1)/4) >>> print a -1.83690953073e-016 > > Thanks, > Nathan P.- Hide quoted text - > > - Show quoted text - -- http://mail.python.org/mailman/listinfo/python-list
