72 lines
1.8 KiB
C
72 lines
1.8 KiB
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_sinh(arg) returns the hyperbolic sine of its floating-
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* point argument.
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*
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* The exponential function is called for arguments
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* greater in magnitude than 0.5.
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*
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* A series is used for arguments smaller in magnitude than 0.5.
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* The coefficients are #2029 from Hart & Cheney. (20.36D)
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*
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* jehanne_cosh(arg) is computed from the exponential function for
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* all arguments.
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*/
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static double p0 = -0.6307673640497716991184787251e+6;
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static double p1 = -0.8991272022039509355398013511e+5;
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static double p2 = -0.2894211355989563807284660366e+4;
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static double p3 = -0.2630563213397497062819489e+2;
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static double q0 = -0.6307673640497716991212077277e+6;
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static double q1 = 0.1521517378790019070696485176e+5;
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static double q2 = -0.173678953558233699533450911e+3;
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double
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jehanne_sinh(double arg)
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{
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double temp, argsq;
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int sign;
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sign = 0;
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if(arg < 0) {
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arg = -arg;
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sign++;
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}
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if(arg > 21) {
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temp = jehanne_exp(arg)/2;
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goto out;
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}
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if(arg > 0.5) {
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temp = (jehanne_exp(arg) - jehanne_exp(-arg))/2;
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goto out;
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}
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argsq = arg*arg;
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temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg;
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temp /= (((argsq+q2)*argsq+q1)*argsq+q0);
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out:
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if(sign)
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temp = -temp;
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return temp;
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}
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double
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jehanne_cosh(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 jehanne_exp(arg)/2;
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return (jehanne_exp(arg) + jehanne_exp(-arg))/2;
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}
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