#include "cephes_mconf.h"

#ifndef _SET_ERRNO
#define _SET_ERRNO(x)
#endif

long double coshl(x)
long double x;
{
long double y;

#ifdef NANS
if( isnanl(x) )
	{
	_SET_ERRNO(EDOM);
	return(x);
  	}
#endif
if( x < 0 )
	x = -x;
if( x > (MAXLOGL + LOGE2L) )
	{
	mtherr( "coshl", OVERFLOW );
	_SET_ERRNO(ERANGE);
#ifdef INFINITIES
	return( INFINITYL );
#else
	return( MAXNUML );
#endif
	}	
if( x >= (MAXLOGL - LOGE2L) )
	{
	y = expl(0.5L * x);
	y = (0.5L * y) * y;
	return(y);
	}
y = expl(x);
y = 0.5L * (y + 1.0L / y);
return( y );
}