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 !. So it would be nice to find a way to solve such a problem. Thanks, Nathan P. -- http://mail.python.org/mailman/listinfo/python-list
