/*  ortho.c    CCMATH mathematics library source code.
 *
 *  Copyright (C)  2000   Daniel A. Atkinson    All rights reserved.
 *  This code may be redistributed under the terms of the GNU library
 *  public license (LGPL). ( See the lgpl.license file for details.)
 * ------------------------------------------------------------------------
 */
#include <math.h>
static double tpi=6.28318530717958647;
void ortho(double *e,int n)
{ int i,j,k,m;
  double *p,*q,c,s,a,unfl();
  for(i=0,p=e; i<n ;++i){
    for(j=0; j<n ;++j){
      if(i==j) *p++ =1.; else *p++ =0.;
     }
   }
  for(i=0,m=n-1; i<m ;++i){
    for(j=i+1; j<n ;++j){
      a=tpi*unfl();
      c=cos(a); s=sin(a);
      p=e+n*i; q=e+n*j;
      for(k=0; k<n ;++k){
        a=*p*c+ *q*s; *q=*q*c- *p*s;
        *p++ =a; ++q;
       }
     }
   }
}