c_div.c

来自「InsightToolkit-1.4.0(有大量的优化算法程序)」· C语言 代码 · 共 48 行

#include "f2c.h"
#include "netlib.h"

/* Modified by Peter Vanroose, June 2001, to allow c being equal to a or b */

#ifdef KR_headers
extern VOID sig_die();
VOID c_div(c, a, b) complex *a; const complex *b, *c;
#else
extern void sig_die(char*, int);
void c_div(complex *c, const complex *a, const complex *b)
#endif
{
  float ratio, den;
  float abr, abi;
  float ar = a->r, ai = a->i;

  if( (abr = b->r) < 0.)
    abr = - abr;
  if( (abi = b->i) < 0.)
    abi = - abi;
  if( abr <= abi ) {
    if(abi == 0) {
#ifdef IEEE_COMPLEX_DIVIDE
      float af, bf;
      af = bf = abr;
      if (a->i != 0 || a->r != 0)
        af = 1.;
      c->i = c->r = af / bf;
      return;
#else
      sig_die("complex division by zero", 1);
#endif
    }
    ratio = b->r / b->i ;
    den = b->i * (1 + ratio*ratio);
    c->r = (ar*ratio + ai) / den;
    c->i = (ai*ratio - ar) / den;
  }

  else {
    ratio = b->i / b->r ;
    den = b->r * (1 + ratio*ratio);
    c->r = (ar + ai*ratio) / den;
    c->i = (ai - ar*ratio) / den;
  }
}