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Annotation of 43BSDTahoe/usr.lib/libF77/z_sqrt.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  *
        !             6:  *     @(#)z_sqrt.c    5.2     11/3/86
        !             7:  */
        !             8: 
        !             9: #include "complex"
        !            10: #ifdef tahoe
        !            11: #include <tahoemath/FP.h>
        !            12: #define cabs zabs
        !            13: #endif tahoe
        !            14: 
        !            15: z_sqrt(r, z)
        !            16: dcomplex *r, *z;
        !            17: {
        !            18: double mag, sqrt(), cabs();
        !            19: 
        !            20: if( (mag = cabs(z->dreal, z->dimag)) == 0.)
        !            21:        r->dreal = r->dimag = 0.;
        !            22: else if(z->dreal > 0)
        !            23:        {
        !            24:        r->dreal = sqrt(0.5 * (mag + z->dreal) );
        !            25:        r->dimag = z->dimag / r->dreal / 2;
        !            26:        }
        !            27: else
        !            28:        {
        !            29:        r->dimag = sqrt(0.5 * (mag - z->dreal) );
        !            30:        if(z->dimag < 0)
        !            31: #ifndef tahoe
        !            32:                r->dimag = - r->dimag;
        !            33: #else tahoe
        !            34:                *((long int *)&r->dimag) ^= SIGN_BIT;
        !            35: #endif tahoe
        !            36:        r->dreal = z->dimag / r->dimag / 2;
        !            37:        }
        !            38: }

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