Szabolcs Nagy
101e601285
acosh(x) is invalid for x<1, acoshf tried to be clever using signed comparisions to handle all x<2 the same way, but the formula was wrong on large negative values.
24 lines
564 B
C
24 lines
564 B
C
#include "libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double acoshl(long double x)
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{
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return acosh(x);
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}
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#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
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/* acosh(x) = log(x + sqrt(x*x-1)) */
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long double acoshl(long double x)
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{
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union ldshape u = {x};
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int e = u.i.se & 0x7fff;
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if (e < 0x3fff + 1)
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/* |x| < 2, invalid if x < 1 or nan */
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return log1pl(x-1 + sqrtl((x-1)*(x-1)+2*(x-1)));
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if (e < 0x3fff + 32)
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/* |x| < 0x1p32 */
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return logl(2*x - 1/(x+sqrtl(x*x-1)));
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return logl(x) + 0.693147180559945309417232121458176568L;
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}
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#endif
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