35 lines
849 B
C
35 lines
849 B
C
/*
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* This file is part of the UCB release of Plan 9. It is subject to the license
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* terms in the LICENSE file found in the top-level directory of this
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* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
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* part of the UCB release of Plan 9, including this file, may be copied,
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* modified, propagated, or distributed except according to the terms contained
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* in the LICENSE file.
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*/
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#include <u.h>
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#include <libc.h>
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/*
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jehanne_tanh(arg) computes the hyperbolic tangent of its floating
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point argument.
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sinh and cosh are called except for large arguments, which
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would cause overflow improperly.
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*/
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double
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jehanne_tanh(double arg)
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{
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if(arg < 0) {
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arg = -arg;
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if(arg > 21)
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return -1;
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return -jehanne_sinh(arg)/jehanne_cosh(arg);
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}
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if(arg > 21)
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return 1;
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return jehanne_sinh(arg)/jehanne_cosh(arg);
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}
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