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Annotation of 3BSD/libF77/pow_zi.c, revision 1.1.1.1

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

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