111 lines
1.8 KiB
C
111 lines
1.8 KiB
C
/* coshl.c
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*
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* Hyperbolic cosine, long double precision
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*
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*
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*
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* SYNOPSIS:
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*
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* long double x, y, coshl();
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*
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* y = coshl( x );
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*
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*
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*
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* DESCRIPTION:
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*
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* Returns hyperbolic cosine of argument in the range MINLOGL to
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* MAXLOGL.
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*
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* cosh(x) = ( exp(x) + exp(-x) )/2.
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*
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*
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*
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* ACCURACY:
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*
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* Relative error:
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* arithmetic domain # trials peak rms
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* IEEE +-10000 30000 1.1e-19 2.8e-20
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*
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*
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* ERROR MESSAGES:
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*
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* message condition value returned
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* cosh overflow |x| > MAXLOGL+LOGE2L INFINITYL
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*
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*
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*/
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/*
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Cephes Math Library Release 2.7: May, 1998
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Copyright 1985, 1991, 1998 by Stephen L. Moshier
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*/
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/*
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Modified for mingw
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2002-07-22 Danny Smith <dannysmith@users.sourceforge.net>
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*/
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#ifdef __MINGW32__
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#include "cephes_mconf.h"
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#else
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#include "mconf.h"
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#endif
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#ifndef _SET_ERRNO
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#define _SET_ERRNO(x)
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#endif
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#ifndef __MINGW32__
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extern long double MAXLOGL, MAXNUML, LOGE2L;
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#ifdef ANSIPROT
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extern long double expl ( long double );
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extern int isnanl ( long double );
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#else
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long double expl(), isnanl();
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#endif
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#ifdef INFINITIES
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extern long double INFINITYL;
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#endif
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#ifdef NANS
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extern long double NANL;
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#endif
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#endif /* __MINGW32__ */
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long double coshl(x)
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long double x;
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{
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long double y;
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#ifdef NANS
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if( isnanl(x) )
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{
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_SET_ERRNO(EDOM);
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return(x);
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}
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#endif
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if( x < 0 )
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x = -x;
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if( x > (MAXLOGL + LOGE2L) )
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{
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mtherr( "coshl", OVERFLOW );
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_SET_ERRNO(ERANGE);
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#ifdef INFINITIES
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return( INFINITYL );
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#else
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return( MAXNUML );
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#endif
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}
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if( x >= (MAXLOGL - LOGE2L) )
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{
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y = expl(0.5L * x);
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y = (0.5L * y) * y;
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return(y);
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}
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y = expl(x);
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y = 0.5L * (y + 1.0L / y);
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return( y );
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}
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