c++,可能是最快的e算法，核心代码只有几行

// evalue.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include 
#include 
#include

//通过泰勒公式的变形：e = 1 + (1/1!) + (1/2!) + (1/3!) + … + (1/n!)   来求e的值
//#define M 1024
//e=2.718281828459
char* e(unsigned int M, char *estring);
int main()
{
	unsigned int i;
	char * estring;
	for (i =200004; i < 200005; i++)
	{
		estring = new char[i+1];
		e(i,estring);
		printf("按任意键继续显示数据ne=");
		printf("%d", estring[0]);
			printf(".");

			for (unsigned int j = 1; j < i; j++)
		{
			if (estring[j] == 13)
				break;
			printf("%d", estring[j]);
			if (j % 1836 == 0)
				_getch();
		}
		printf("n");
		delete estring;
	}
	

	return 0;
}
//通过泰勒公式的变形：e = 1 + (1/n!)+ … +(1/3!) + (1/2!) + (1/1!)  来求e的值
char *e(unsigned int M,char *estring)
{
	unsigned long k = 0, i = 0, j = 0, sum = 0, E,F,G,H,tmp,n,m;
	unsigned long *yushu;
	unsigned int elength;
	clock_t startTime, endTime;
	startTime = clock();//计时开始
	if (M > 429496720) M = 429496720;
	n = (unsigned long)log10((long double)M);
	if (n > 3)
	{
		n = 10 - n;
		if (n > 5) n = 5;//以防超界
	}
	else
	{
		if(n==0)
			n = 1;
	}
	elength = M / n;
	E = 1;
	for (i = 0; i < n-1; i++)
		E = E * 10;
	F = 10 * E; H = E;
	yushu = new unsigned long[M + 1];
	for (k = 0; k <= M; k++)
		yushu[k] = E;
	k = 0;
	printf("e 值正在计算，一共要计算 %lu次，数据长度%lun", elength,n*elength);
	for (i = 1; i <= elength; i++)
	{
		if (i % 1000 == 0)
			printf("已经计算 %lu 次,完成%%%.1fn",i, (long double)i / (long double)elength * 100);
		for (j = M, sum = 0; j > 0; j--)
		{
			sum += yushu[j] * F;//
			yushu[j] = sum % (j);
			sum /= (j);
		}
		tmp = E + sum / F;
		G = H;
		for (m = 0; m < n; m++)
		{
			estring[k++] = tmp / G; tmp = tmp % G; G = G / 10;

		}
		E = sum % F;
	}
	estring[k] = 13;//终止符标志
	printf("n数据长度 %lun", n*(i-1));
	delete yushu;
	endTime = clock();//计时结束
	printf("计算时间: %.1f 秒",(double)(endTime - startTime) / CLOCKS_PER_SEC);
	return estring;

}