30 lines
412 B
C
30 lines
412 B
C
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/*
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* compute 10**x by successive squaring.
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*/
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#include <_ansi.h>
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double
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_DEFUN (__exp10, (x),
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unsigned x)
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{
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static _CONST double powtab[] =
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{1.0,
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10.0,
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100.0,
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1000.0,
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10000.0};
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if (x < (sizeof (powtab) / sizeof (double)))
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return powtab[x];
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else if (x & 1)
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{
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return 10.0 * __exp10 (x - 1);
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}
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else
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{
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double n = __exp10 (x / 2);
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return n * n;
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}
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}
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