/*
 * You may think you know what the following code does.
 * But you dont. Trust me.
 * Fiddle with it, and youll spend many a sleepless
 * night cursing the moment you thought youd be clever
 * enough to "optimize" the code below.
 * Now close this file and go play with something else.
 */ 

从《雷神之锤III》的资料中，我在一些随机的帖子中偶然发现了这一点。该文件的完整源代码可以在这里找到。这是一种非常快速的求平方根倒数的方法。至于最好的评论呢?当然，这是一种常见的方法，但考虑到它附着在直线上，它的神奇之处在于它的伟大之处。

float Q_rsqrt( float number )
{
  long i;
  float x2, y;
  const float threehalfs = 1.5F;

  x2 = number * 0.5F;
  y  = number;
  i  = * ( long * ) &y;  // evil floating point bit level hacking
  i  = 0x5f3759df - ( i >> 1 ); // what the fuck?
  y  = * ( float * ) &i;
  y  = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
  // y  = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed

  #ifndef Q3_VM
  #ifdef __linux__
    assert( !isnan(y) ); // bk010122 - FPE?
  #endif
  #endif
  return y;
}

catch (Exception ex)
{ 
    // just die already.
}

在20世纪80年代早期的某个时候，我们在PL/I中为公用事业编写财务建模代码。接到一个客户的电话，说代码在评论之后就爆炸了

/* Honest this works */

这家伙用了我们的标准金融方程花了大约15页的代数把一堆代码组合成一个方程。在三里岛事件后，当公用事业公司不得不以巨大的代价注销他们的核电站时，这个方程失败了，因为FIXED BIN 15(整数)溢出，如果代数没有发生，就不会发生这种溢出。

在linux 1.0内核调度器(schedule .c)中:

Dijkstra可能讨厌我。

/*
 *  'schedule()' is the scheduler function. It's a very simple and nice
 * scheduler: it's not perfect, but certainly works for most things.
 * The one thing you might take a look at is the signal-handler code here.
 *
 *   NOTE!!  Task 0 is the 'idle' task, which gets called when no other
 * tasks can run. It can not be killed, and it cannot sleep. The 'state'
 * information in task[0] is never used.
 *
 * The "confuse_gcc" goto is used only to get better assembly code..
 * Dijkstra probably hates me.
 */
asmlinkage void schedule(void)

(…)

virgin = 0;     /* you're not a virgin anymore, sweety */