stl_numeric.h里面的都是数值算法，与数值计算有关。
G++ 2.91.57，cygnus\cygwin-b20\include\g++\stl_numeric.h 完整列表
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/* NOTE: This is an internal header file, included by other STL headers.
* You should not attempt to use it directly.
*/
#ifndef __SGI_STL_INTERNAL_NUMERIC_H
#define __SGI_STL_INTERNAL_NUMERIC_H
__STL_BEGIN_NAMESPACE
//计算init和[first last)区间元素的和
// 版本一
template <class InputIterator, class T>
T accumulate(InputIterator first, InputIterator last, T init) {
for ( ; first != last; ++first)
init = init + *first; // 每个元素的初值累加到init上
return init;
}
// 版本二
template <class InputIterator, class T, class BinaryOperation>
T accumulate(InputIterator first, InputIterator last, T init,
BinaryOperation binary_op) {
for ( ; first != last; ++first)
init = binary_op(init, *first); // 对每一个元素执行二元操作
return init;
}
//计算两段元素的内积，要提供初始值init。两段元素一样长，所以第二段没提供last2
// 版本一
template <class InputIterator1, class InputIterator2, class T>
T inner_product(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, T init) {
for ( ; first1 != last1; ++first1, ++first2)
init = init + (*first1 * *first2); // 执行两个序列的一般內積
return init;
}
// 版本二
template <class InputIterator1, class InputIterator2, class T,
class BinaryOperation1, class BinaryOperation2>
T inner_product(InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, T init, BinaryOperation1 binary_op1,
BinaryOperation2 binary_op2) {
for ( ; first1 != last1; ++first1, ++first2)
// 以外界提供的仿函数来取代第一版本中的 operator* 和 operator+。
// op2 作用域两元素间，op1用于op2之结果与init之间。
init = binary_op1(init, binary_op2(*first1, *first2));
return init;
}
//__partial_sum定义在partial_sum前面，后者调用前者
template <class InputIterator, class OutputIterator, class T>
OutputIterator __partial_sum(InputIterator first, InputIterator last,
OutputIterator result, T*) {
T value = *first;
while (++first != last) {
value = value + *first; // 前n个元素的总和
*++result = value; // 指定给目的端
}
return ++result;
}
// 版本一
template <class InputIterator, class OutputIterator>
OutputIterator partial_sum(InputIterator first, InputIterator last,
OutputIterator result) {
if (first == last) return result;
*result = *first;
return __partial_sum(first, last, result, value_type(first));
// 侯捷认为（并证实证），不需像上行那样转呼叫，可改用以下写法（整个函式）：
// if (first == last) return result;
// *result = *first;
// iterator_traits<InputIterator>::value_type value = *first;
// while (++first != last) {
// value = value + *first;
// *++result = value;
// }
// return ++result;
// 这样的观念和作法，适用于本当所有函数
}
template <class InputIterator, class OutputIterator, class T,
class BinaryOperation>
OutputIterator __partial_sum(InputIterator first, InputIterator last,
OutputIterator result, T*,
BinaryOperation binary_op) {
T value = *first;
while (++first != last) {
value = binary_op(value, *first);
*++result = value;
}
return ++result;
}
// 版本二
template <class InputIterator, class OutputIterator, class BinaryOperation>
OutputIterator partial_sum(InputIterator first, InputIterator last,
OutputIterator result, BinaryOperation binary_op) {
if (first == last) return result;
*result = *first;
return __partial_sum(first, last, result, value_type(first), binary_op);
// 侯捷认为（并证实证），不需像上行那样转呼叫，可改用以下写法（整个函式）：
// if (first == last) return result;
// *result = *first;
// iterator_trait<InputIterator>::value_type value = *first;
// while (++first != last) {
// value = binary_op(value, *first);
// *++result = value;
// }
// return ++result;
//
// 这样的观念和作法，适用于本当所有函数
}
template <class InputIterator, class OutputIterator, class T>
OutputIterator __adjacent_difference(InputIterator first, InputIterator last,
OutputIterator result, T*) {
T value = *first;
while (++first != last) { // 走过整个范围
T tmp = *first;
*++result = tmp - value; // 将两个相邻元素的差额（后-前），指派给目的端
value = tmp;
}
return ++result;
}
// 版本一
template <class InputIterator, class OutputIterator>
OutputIterator adjacent_difference(InputIterator first, InputIterator last,
OutputIterator result) {
if (first == last) return result;
*result = *first; // 首先记录第一个元素
return __adjacent_difference(first, last, result, value_type(first));
}
template <class InputIterator, class OutputIterator, class T,
class BinaryOperation>
OutputIterator __adjacent_difference(InputIterator first, InputIterator last,
OutputIterator result, T*,
BinaryOperation binary_op) {
T value = *first;
while (++first != last) {
T tmp = *first;
*++result = binary_op(tmp, value); // 将相邻两元素的运算結果，指派给目的端
value = tmp;
}
return ++result;
}
// 版本二
template <class InputIterator, class OutputIterator, class BinaryOperation>
OutputIterator adjacent_difference(InputIterator first, InputIterator last,
OutputIterator result,
BinaryOperation binary_op) {
if (first == last) return result;
*result = *first;
return __adjacent_difference(first, last, result, value_type(first),
binary_op);
}
//power为SGI专属，并不在STL标准之列，它用来计算某数的n幂次方。
//这里所谓的n幂次方是指对自己进行某种运算n次，运算类型可由外界执行。如果是乘法则就是乘幂。
// 版本二，冪次方。如果指定为乘法运算，则当n >= 0 时传回 x ** n。
// 注意，"multiplication" 必须满足结合律（associative），
// 但不需满足交换律（commutative）。
template <class T, class Integer, class MonoidOperation>
T power(T x, Integer n, MonoidOperation op) {
if (n == 0)
return identity_element(op); // 取出「证同元素」identity element.证同元素在后面章节介绍
else {
while ((n & 1) == 0) {
n >>= 1;
x = op(x, x);//两个参数都是x。因为每次n减小1倍(n是偶数，因为n&1=0)
}
T result = x;
n >>= 1;
while (n != 0) {
x = op(x, x);
if ((n & 1) != 0)
result = op(result, x);
n >>= 1;
}
return result;
}
}
// 版本一，乘冪。
template <class T, class Integer>
inline T power(T x, Integer n) {
return power(x, n, multiplies<T>());
}
// 侯捷：iota 是什麼的缩写？
// 函数意义：在 [first,last) 范围内內填入value, value+1, value+2...。
template <class ForwardIterator, class T>
void iota(ForwardIterator first, ForwardIterator last, T value) {
while (first != last) *first++ = value++;
}
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_NUMERIC_H */
// Local Variables:
// mode:C++
// End:
《STL源码剖析》---stl_numeric.h阅读笔记,布布扣,bubuko.com
原文地址：http://blog.csdn.net/kangroger/article/details/38663785
