don't use 'cc -f' with compilers that don't do automatic double to

[unix-history] / usr / src / usr.bin / f77 / libF77 / c_sqrt.c

/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)c_sqrt.c    5.2     %G%
*/

#include "complex"
#ifdef tahoe
#include <tahoemath/FP.h>
#endif tahoe

c_sqrt(r, z)
complex *r, *z;
{
double mag, sqrt(), cabs();

if( (mag = cabs(z->real, z->imag)) == 0.)
       r->real = r->imag = 0.;
else if(z->real > 0)
       {
       r->real = sqrt(0.5 * (mag + z->real) );
       r->imag = z->imag / r->real / 2;
       }
else
       {
       r->imag = sqrt(0.5 * (mag - z->real) );
       if(z->imag < 0)
#ifndef tahoe
               r->imag = - r->imag;
#else tahoe
               *(unsigned long*)&(r->imag) ^= SIGN_BIT;
#endif tahoe
       r->real = z->imag / r->imag /2;
       }
}