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Annotation of 42BSD/usr.lib/libF77/pow_zi.c, revision 1.1

1.1     ! root        1: /*
        !             2:  *     "@(#)pow_zi.c   1.1"
        !             3:  */
        !             4: 
        !             5: #include "complex"
        !             6: 
        !             7: pow_zi(p, a, b)        /* p = a**b  */
        !             8: dcomplex *p, *a;
        !             9: long int *b;
        !            10: {
        !            11: long int n;
        !            12: double t;
        !            13: dcomplex x;
        !            14: 
        !            15: n = *b;
        !            16: p->dreal = 1;
        !            17: p->dimag = 0;
        !            18: 
        !            19: if(n == 0)
        !            20:        return;
        !            21: if(n < 0)
        !            22:        {
        !            23:        n = -n;
        !            24:        z_div(&x, p, a);
        !            25:        }
        !            26: else
        !            27:        {
        !            28:        x.dreal = a->dreal;
        !            29:        x.dimag = a->dimag;
        !            30:        }
        !            31: 
        !            32: for( ; ; )
        !            33:        {
        !            34:        if(n & 01)
        !            35:                {
        !            36:                t = p->dreal * x.dreal - p->dimag * x.dimag;
        !            37:                p->dimag = p->dreal * x.dimag + p->dimag * x.dreal;
        !            38:                p->dreal = t;
        !            39:                }
        !            40:        if(n >>= 1)
        !            41:                {
        !            42:                t = x.dreal * x.dreal - x.dimag * x.dimag;
        !            43:                x.dimag = 2 * x.dreal * x.dimag;
        !            44:                x.dreal = t;
        !            45:                }
        !            46:        else
        !            47:                break;
        !            48:        }
        !            49: }

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