factorial

I am using unsigned long long integer format in order to calculate big factorials. However my code fails at some point can you have a look at it? Actually it is part of a larger code for Taylor expansion of exponential function, but that part is irrelevant at this point. I will appreciate any suggestions. Thanks #include <stdio.h> #include <math.h> //We need to write a factorial function beforehand, since we //have factorial in the denominators. //Remembering that factorials are defined for integers; it is //possible to define factorials of non-integer numbers using //Gamma Function but we

I know how to do memoization in Python easily but I need a faster way to compute them, so I am using C++. However, I have no clue how to memoize. I understand that it's about storing values into an array or vector and then scanning for its value when retrieving, but it'd be really helpful to see how this is done so I can try its speed. Well the neatest way I can think of to do this in C++ is probably using a function object to store the memoized values. I guess this is probably slightly similar to your python decorator, although I have never really done any python. The code would look

I found this page describing a number of algorithms for computing the factorial. Unfortunately, the explanations are terse and I don't feel like sifting through line after line of source code to understand the basic principles behind the algorithms. Can anybody point me to more detailed descriptions of these (or other fast) algorithms for computing the factorial? Edit: This page describes the method of prime factorization, the technique common to all of the best-performing factorial algorithms. It also contains some nice example code in Python. The author links to a description of binary

What is an example (in code) of a O(n!) function? It should take appropriate number of operations to run in reference to n ; that is, I'm asking about time complexity. sepp2k There you go. This is probably the most trivial example of a function that runs in O(n!) time (where n is the argument to the function): void nFacRuntimeFunc(int n) { for(int i=0; i<n; i++) { nFacRuntimeFunc(n-1); } } One classic example is the traveling salesman problem through brute-force search. If there are N cities, the brute force method will try each and every permutation of these N cities to find which one is

I tried to calculate poisson distribution in python as below: p = math.pow(3,idx) depart = math.exp(-3) * p depart = depart / math.factorial(idx) idx ranges from 0 But I got OverflowError: long int too large to convert to float I tried to convert depart to float but no results. Factorials get large real fast : >>> math.factorial(170)

The below does not compile: Func<int, int> fac = n => (n <= 1) ? 1 : n * fac(n - 1); Local variable 'fac' might not be initialized before accessing How can you make a recursive function with lambdas? [Update] Here are also two links that I found interesting to read: Eric Lippert's "Why does a recursive lambda cause a definite assignment error?" Anonymous Recursion in C# This particular style of function is not supported by C# as a single line declaration. You have to separate out the declaration and definition into 2 lines Func<int, int> fac = null; fac = n => (n <= 1) ? 1 : n * fac(n - 1);