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documentation update for double_factorial

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Krishna Vedala
2020-05-27 14:07:05 -04:00
parent 50070774dd
commit d723604e01
1 changed files with 7 additions and 3 deletions
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10
math/double_factorial.cpp
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@@ -1,5 +1,7 @@
/**
* @file
* @brief Compute double factorial: \f$n!!\f$
*
* Double factorial of a non-negative integer n, is defined as the product of
* all the integers from 1 to n that have the same parity (odd or even) as n.
* <br/>It is also called as semifactorial of a number and is denoted by
@@ -9,7 +11,8 @@
#include <cassert>
#include <iostream>
/// Compute double factorial using iterative method
/** Compute double factorial using iterative method
*/
uint64_t double_factorial_iterative(uint64_t n) {
uint64_t res = 1;
for (uint64_t i = n;; i -= 2) {
@@ -19,8 +22,9 @@ uint64_t double_factorial_iterative(uint64_t n) {
return res;
}
/// Compute double factorial using resursive method.
// <br/>Recursion can be costly for large numbers.
/** Compute double factorial using resursive method.
* <br/>Recursion can be costly for large numbers.
*/
uint64_t double_factorial_recursive(uint64_t n) {
if (n <= 1) return 1;
return n * double_factorial_recursive(n - 2);