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Annotation of researchv8dc/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: static dcomplex one = {1.0, 0.0};
                     11: 
                     12: n = *b;
                     13: p->dreal = 1;
                     14: p->dimag = 0;
                     15: 
                     16: if(n == 0)
                     17:        return;
                     18: if(n < 0)
                     19:        {
                     20:        n = -n;
                     21:        z_div(&x, &one, a);
                     22:        }
                     23: else
                     24:        {
                     25:        x.dreal = a->dreal;
                     26:        x.dimag = a->dimag;
                     27:        }
                     28: 
                     29: for( ; ; )
                     30:        {
                     31:        if(n & 01)
                     32:                {
                     33:                t = p->dreal * x.dreal - p->dimag * x.dimag;
                     34:                p->dimag = p->dreal * x.dimag + p->dimag * x.dreal;
                     35:                p->dreal = t;
                     36:                }
                     37:        if(n >>= 1)
                     38:                {
                     39:                t = x.dreal * x.dreal - x.dimag * x.dimag;
                     40:                x.dimag = 2 * x.dreal * x.dimag;
                     41:                x.dreal = t;
                     42:                }
                     43:        else
                     44:                break;
                     45:        }
                     46: }

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