On Feb 20, 8:13 pm, mukesh tiwari <mukeshtiwari.ii...@gmail.com> wrote: > On Feb 20, 5:44 pm, Mark Dickinson <dicki...@gmail.com> wrote: > > > > > > > On Feb 20, 11:17 am, mukesh tiwari <mukeshtiwari.ii...@gmail.com> > > wrote: > > > > Hello everyone. I think it is related to the precision with double > > > arithmetic so i posted here.I am trying with this problem > > > (https://www.spoj.pl/problems/CALCULAT) and the problem say that "Note : > > > for > > > all test cases whose N>=100, its K<=15." I know precision of doubles > > > in c is 16 digits. Could some one please help me with this precision > > > issue.I used stirling (http://en.wikipedia.org/wiki/ > > > Stirling's_approximation) to calculate the first k digits of N. > > > Thank you. > > > If I understand you correctly, you're trying to compute the first k > > digits in the decimal expansion of N!, with bounds of k <= 15 and 100 > > <= N < 10**8. Is that right? > > > Python's floats simply don't give you enough precision for this: > > you'd need to find the fractional part of log10(N!) with >= 15 digits > > of precision. But the integral part needs ~ log10(log10(N!)) digits, > > so you end up needing to compute log10(N!) with at least 15 + > > log10(log10(N!)) ~ 15 + log10(N) + log10(log10(N)) digits (plus a few > > extra digits for safety); so that's at least 25 digits needed for N > > close to 10**8. > > > The decimal module would get you the results you need (are you allowed > > imports?). Or you could roll your own log implementation based on > > integer arithmetic. > > > -- > > Mark > > Yes i am trying to first k digits of N!.I will try your method. > Thank you
I am out of luck.I put d_2=d_1-int(d_1)+25 instead of d_2=d_1- int(d_1)+K-1 but i am getting WA. "The decimal module would get you the results you need (are you allowed imports?). Or you could roll your own log implementation based on integer arithmetic. " I don't know if is possible to import this decimal module but kindly tell me.Also a bit about log implementation Thank you -- http://mail.python.org/mailman/listinfo/python-list
