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Annotation of 43BSDReno/lib/libF77/pow_di.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_di.c    5.3     1/19/88
                      7:  */
                      8: 
                      9: double
                     10: pow_di(ap, bp)
                     11:        double *ap;
                     12:        long *bp;
                     13: {
                     14:        register long n = *bp;
                     15:        double y, x = *ap;
                     16: 
                     17:        if (!n)
                     18:                return((double)1);
                     19:        if (n < 0) {
                     20:                x = (double)1 / x;
                     21:                n = -n;
                     22:        }
                     23:        while (!(n&1)) {
                     24:                x *= x;
                     25:                n >>= 1;
                     26:        }
                     27:        for (y = x; --n > 0; y *= x)
                     28:                while (!(n&1)) {
                     29:                        x *= x;
                     30:                        n >>= 1;
                     31:                }
                     32:        return(y);
                     33: }

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