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+/* Copyright (C) 1991 1995 Free Software Foundation, Inc.
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * As a special exception, the Free Software Foundation gives permission
+ * for additional uses of the text contained in its release of GUILE.
+ *
+ * The exception is that, if you link the GUILE library with other files
+ * to produce an executable, this does not by itself cause the
+ * resulting executable to be covered by the GNU General Public License.
+ * Your use of that executable is in no way restricted on account of
+ * linking the GUILE library code into it.
+ *
+ * This exception does not however invalidate any other reasons why
+ * the executable file might be covered by the GNU General Public License.
+ *
+ * This exception applies only to the code released by the
+ * Free Software Foundation under the name GUILE.  If you copy
+ * code from other Free Software Foundation releases into a copy of
+ * GUILE, as the General Public License permits, the exception does
+ * not apply to the code that you add in this way.  To avoid misleading
+ * anyone as to the status of such modified files, you must delete
+ * this exception notice from them.
+ *
+ * If you write modifications of your own for GUILE, it is your choice
+ * whether to permit this exception to apply to your modifications.
+ * If you do not wish that, delete this exception notice.  
+ */
+
+/* "pi.c", program for computing digits of numerical value of PI.
+   Author: Aubrey Jaffer
+
+pi <n> <d> prints out <n> digits of pi in groups of <d> digits.
+
+'Spigot' algorithm origionally due to Stanly Rabinowitz.
+This algorithm takes time proportional to the square of <n>/<d>.
+This fact can make comparisons of computational speed between systems
+of vastly differring performances quicker and more accurate.
+
+Try: pi 100 5
+The digit size <d> will have to be reduced for larger <n> or an
+error due to overflow will occur. */
+
+short *calloc();
+main(c,v)
+int c;char **v;{
+  int n=200,j=0,m,b=2,k=0,t,r=1,d=5;
+  long q;
+  short *a;
+  if(c>1)n=atoi(v[1]);
+  if(c>2)d=atoi(v[2]);
+  while(k++<d)r=r*10;
+  n=n/d+1;
+  k=m=3.322*n*d;
+  a=calloc(1+m,2);
+  while(k)a[--k]=2;
+  for(a[m]=4;j<n;b=q%r){
+    q=0;
+    for(k=m;k;){
+      q+=a[k]*r;
+      t=(2*k+1);
+      a[k]=q%t;
+      q=q/t;
+      q*=k--;}
+    printf("%0*d%s",d,b+q/r,++j%10?"  ":"\n");}
+  puts("");}