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//
// IFDGAMMA     : gamma function for DOUBLE PRECISION argument
//

#include "fmath.h"
#include <float.h>

#include "ftnstd.h"
#include "ifenv.h"

extern  extended                __gamma(extended,const extended __FAR *);

static  const double __FAR  xinf  = { DBL_MAX };
static  const double __FAR  xmin  = { DBL_MIN };
static  const double __FAR  big   = { 171.0e0 };

double  DGAMMA( double arg ) {
//============================

    if( fabs( arg ) <= xmin ) {
        if( arg <= 0.0 ) {
            return( -xinf );
        } else {
            return( xinf );
        }
    } else if( fabs( arg ) >= big ) {
        return( xinf );
    }
    return( __gamma( arg, &xinf ) );
}

#if _OPT_CG == _ON

double XDGAMMA( double *arg ) {
//=============================

    return( DGAMMA( *arg ) );
}

#endif
