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Annotation of coherent/b/bin/as/_pow10.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * C general utilities library internals.
                      3:  * _pow10()
                      4:  * Compute 10.0^n.
                      5:  */
                      6: 
                      7: /*
                      8:  * There are lots of ways to do this, with varying accuracy and speed.
                      9:  * Using recursion on all negative exponents eliminates the divide
                     10:  * but introduces greater roundoff errors.
                     11:  */
                     12: 
                     13: static double powtab[] = {
                     14:        1e-16,  1e-15,  1e-14,  1e-13,  1e-12,  1e-11,  1e-10,  1e-9,
                     15:        1e-8,   1e-7,   1e-6,   1e-5,   1e-4,   1e-3,   1e-2,   1e-1,
                     16:        1e0,
                     17:        1e1,    1e2,    1e3,    1e4,    1e5,    1e6,    1e7,    1e8,
                     18:        1e9,    1e10,   1e11,   1e12,   1e13,   1e14,   1e15,   1e16
                     19: };
                     20: 
                     21: double
                     22: _pow10(exp) register int exp;
                     23: {
                     24: 
                     25:        if (exp < -16)
                     26:                return (1.0/_pow10(-exp));
                     27:        else if (exp <= 16)
                     28:                return (powtab[exp+16]);
                     29:        else if (exp <= 64)
                     30:                return (1e16 * _pow10(exp - 16));
                     31:        else
                     32:                return (1e64 * _pow10(exp - 64));
                     33: }

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