ifgamma.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 70 行

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//
// IFGAMMA      : gamma function for REAL argument
//

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

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

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

static  const extended __FAR    xinf = { FLT_MAX };
static  const single __FAR      xmin = { FLT_MIN };
static  const single __FAR      big = { 34.844 };


single GAMMA( single 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 ) );
}

single XGAMMA( single *arg ) {
//============================

    return( GAMMA( *arg ) );
}