在C中寻找Pi的算法 [英] algorithm for finding Pi in C

问题描述

大家好，


见： - http://mathforum.org/library/drmath/view/54456.html

解决方案

aa ***** @ gmail.com 写道：

大家好，


请参阅： - http://mathforum.org/library/drmath/view/54456.html

这对我有用：


#include< float.h>

/ *

** pi ==（atan（1.0 / 3）+ atan（1.0 / 2））* 4

* /

静态双fs_pi（无效）;


静态双fs_pi（无效）

{

无符号n;

加倍a，b;

静态双p;

static int initialized;


if（！initialized）{

initialized = 1;

n = 1;

a = 3;

do {

a / = 9;

b = a / n;

n + = 2;

a / = 9;

b - = a / n;

n + = 2;

p + = b;

} while（b DBL_EPSILON / 4）;

n = 1;

a = 2;

做{

a / = 4;

b = a / n;

n + = 2;

a / = 4;

b - = a / n;

n + = 2;

p + = b;

}而（b DBL_EPSILON / 2）;

p * = 4;

}

返回p;

}


-

pete

aa ***** @ gmail.com 说：

大家好，


见： - http://mathforum.org/library/drmath /view/54456.html

大概你想要Pi？简单。它大约是3.


-

Richard Heathfield< http://www.cpax.org.uk>

电子邮件：-http：// www。 + rjh @

谷歌用户：< http://www.cpax.org.uk/prg/writings/googly.php>

Usenet是一个奇怪的放置" - dmr 1999年7月29日

5月24日下午2：44 *，Richard Heathfield< r ... @ see.sig.invalidwrote：
< blockquote class =post_quotes>
aark ... @ gmail.com说：

大家好，

见：-http：//mathforum.org/library/drmath/view/54456.html

大概你想要Pi ？简单。它大概是3.

所以我们不需要任意无限制 仅限时间和

内存空间精确度？


在所有情况下，3.14都不是更好的答案吗？这就是最普遍的极客b&b。请记住数学课。


并且通常不是#define const？

>

-

Richard Heathfield< http://www.cpax.org.uk>

电子邮件：-http：// www。 + rjh @

谷歌用户：< http://www.cpax.org.uk/prg/writings/googly.php>

Usenet是一个奇怪的放置" - 1999年7月29日dmr

Hi all,

see:- http://mathforum.org/library/drmath/view/54456.html

解决方案

aa*****@gmail.com wrote:

Hi all,

see:- http://mathforum.org/library/drmath/view/54456.html

This works for me:

#include <float.h>
/*
** pi == (atan(1.0 / 3) + atan(1.0 / 2)) * 4
*/
static double fs_pi(void);

static double fs_pi(void)
{
unsigned n;
double a, b;
static double p;
static int initialized;

if (!initialized) {
initialized = 1;
n = 1;
a = 3;
do {
a /= 9;
b = a / n;
n += 2;
a /= 9;
b -= a / n;
n += 2;
p += b;
} while (b DBL_EPSILON / 4);
n = 1;
a = 2;
do {
a /= 4;
b = a / n;
n += 2;
a /= 4;
b -= a / n;
n += 2;
p += b;
} while (b DBL_EPSILON / 2);
p *= 4;
}
return p;
}

--
pete

aa*****@gmail.com said:

Hi all,

see:- http://mathforum.org/library/drmath/view/54456.html

Presumably you want Pi? Easy. It''s about 3.

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

On May 24, 2:44*pm, Richard Heathfield <[e-mail]:

[e-mail] said:

Hi all,

see:-http://mathforum.org/library/drmath/view/54456.html

Presumably you want Pi? Easy. It''s about 3.

So we doan'' need no arbitrary "unlimited" "limited only by time and
memory space" precision?

Wouldn''t 3.14 be a better answer in all cases? That''s what most
"normal geeks" remember from math class.

And isn''t usually a #define const?

>
--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

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