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Annotation of 43BSDTahoe/usr.lib/libF77/c_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:  *     @(#)c_sqrt.c    5.2     11/3/86
        !             7:  */
        !             8: 
        !             9: #include "complex"
        !            10: #ifdef tahoe
        !            11: #include <tahoemath/FP.h>
        !            12: #endif tahoe
        !            13: 
        !            14: c_sqrt(r, z)
        !            15: complex *r, *z;
        !            16: {
        !            17: double mag, sqrt(), cabs();
        !            18: 
        !            19: if( (mag = cabs(z->real, z->imag)) == 0.)
        !            20:        r->real = r->imag = 0.;
        !            21: else if(z->real > 0)
        !            22:        {
        !            23:        r->real = sqrt(0.5 * (mag + z->real) );
        !            24:        r->imag = z->imag / r->real / 2;
        !            25:        }
        !            26: else
        !            27:        {
        !            28:        r->imag = sqrt(0.5 * (mag - z->real) );
        !            29:        if(z->imag < 0)
        !            30: #ifndef tahoe
        !            31:                r->imag = - r->imag;
        !            32: #else tahoe
        !            33:                *(unsigned long*)&(r->imag) ^= SIGN_BIT;
        !            34: #endif tahoe
        !            35:        r->real = z->imag / r->imag /2;
        !            36:        }
        !            37: }

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