43 lines
750 B
C
43 lines
750 B
C
/*
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nexttoward.c
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Contributed by Danny Smith <dannysmith@users.sourceforge.net>
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No copyright claimed, absolutely no warranties.
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2005-05-10
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*/
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#include <math.h>
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double
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nexttoward (double x, long double y)
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{
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union
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{
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double d;
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unsigned long long ll;
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} u;
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long double xx = x;
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if (isnan (y) || isnan (x))
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return x + y;
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if (xx == y)
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/* nextafter (0.0, -O.0) should return -0.0. */
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return y;
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u.d = x;
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if (x == 0.0)
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{
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u.ll = 1;
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return y > 0.0L ? u.d : -u.d;
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}
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/* Non-extended encodings are lexicographically ordered,
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with implicit "normal" bit. */
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if (((x > 0.0) ^ (y > xx)) == 0)
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u.ll++;
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else
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u.ll--;
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return u.d;
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}
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