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Annotation of 43BSDReno/lib/libF77/pow_zi.c, revision 1.1.1.1

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:  *     @(#)pow_zi.c    5.2     1/24/88
                      7:  */
                      8: 
                      9: #include "complex"
                     10: 
                     11: #define        Z_MULEQ(A,B)    \
                     12:        t = (A).dreal * (B).dreal - (A).dimag * (B).dimag,\
                     13:        (A).dimag = (A).dreal * (B).dimag + (A).dimag * (B).dreal,\
                     14:        (A).dreal = t   /* A *= B */
                     15: 
                     16: void
                     17: pow_zi(p, a, b)        /* p = a**b  */
                     18:        dcomplex *p, *a;
                     19:        long int *b;
                     20: {
                     21:        register long n = *b;
                     22:        double t;
                     23:        dcomplex x;
                     24: 
                     25:        x = *a;
                     26:        p->dreal = (double)1, p->dimag = (double)0;
                     27:        if (!n)
                     28:                return;
                     29:        if (n < 0) {
                     30:                z_div(&x, p, a);
                     31:                n = -n;
                     32:        }
                     33:        while (!(n&1)) {
                     34:                Z_MULEQ(x, x);
                     35:                n >>= 1;
                     36:        }
                     37:        for (*p = x; --n > 0; Z_MULEQ(*p, x))
                     38:                while (!(n&1)) {
                     39:                        Z_MULEQ(x, x);
                     40:                        n >>= 1;
                     41:                }
                     42: }

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