예제 #1
0
inline long double ibeta(long double a, long double b, long double x)
{
#ifdef BOOST_MSVC
   return incbet((double)a, (double)b, (double)x); 
#else
   return incbetl(a, b); 
#endif
}
예제 #2
0
파일: fdtr.c 프로젝트: mandrakos/mglib
double fdtrc(double a, double b, double x)
{
    double w;

    if ((a <= 0.0) || (b <= 0.0) || (x < 0.0)) {
        mtherr("fdtrc", DOMAIN);
        return CEPHES_NAN;
    }
    w = b / (b + a * x);
    return incbet(0.5 * b, 0.5 * a, w);
}
예제 #3
0
파일: fdtr.c 프로젝트: mandrakos/mglib
double fdtr(double a, double b, double x)
{
    double w;

    if ((a <= 0.0) || (b <= 0.0) || (x < 0.0)) {
        mtherr("fdtr", DOMAIN);
        return CEPHES_NAN;
    }
    w = a * x;
    w = w / (b + w);
    return incbet(0.5 * a, 0.5 * b, w);
}
예제 #4
0
파일: fdtr.c 프로젝트: mandrakos/mglib
double fdtri(double a, double b, double y)
{
    double w, x;

    if ((a <= 0.0) || (b <= 0.0) || (y <= 0.0) || (y > 1.0)) {
        mtherr("fdtri", DOMAIN);
        return CEPHES_NAN;
    }
    y = 1.0 - y;
    /* Compute probability for x = 0.5.  */
    w = incbet(0.5 * b, 0.5 * a, 0.5);
    /* If that is greater than y, then the solution w < .5.
     * Otherwise, solve at 1-y to remove cancellation in (b - b*w).  */
    if (w > y || y < 0.001) {
        w = incbi(0.5 * b, 0.5 * a, y);
        x = (b - b * w) / (a * w);
    }
    else {
        w = incbi(0.5 * a, 0.5 * b, 1.0 - y);
        x = b * w / (a * (1.0 - w));
    }
    return x;
}
예제 #5
0
double btdtr( double a, double b, double x )
{
    return( incbet( a, b, x ) );
}
예제 #6
0
inline double ibeta(double a, double b, double x)
{ return incbet(a, b, x); }
예제 #7
0
파일: stdtr.c 프로젝트: agaurav/QT-GRETL
double stdtr (double rk, double t)
{
    double x, z, f, tz, p, xsqk;
    int k, j, is_int;

    if (rk <= 0) {
	mtherr("stdtr", CEPHES_DOMAIN);
	return 0.0;
    } else {
	k = (int) rk;
	is_int = (rk - k) == 0.0;
    }

    if (t == 0) {
	return 0.5;
    }

    if (t < -2.0) {
	z = rk / (rk + t * t);
	p = 0.5 * incbet(0.5*rk, 0.5, z);
	return p;
    }

    if (is_int) {
	/* integer df */

	/*	compute integral from -t to +t */

	if (t < 0) {
	    x = -t;
	} else {
	    x = t;
	}

	z = 1.0 + (x * x)/rk;

	/* test if k is odd or even */
	if ((k & 1) != 0) {

	    /* computation for odd k */

	    xsqk = x/sqrt(rk);
	    p = atan(xsqk);
	    if (k > 1) {
		f = 1.0;
		tz = 1.0;
		j = 3;
		while ((j <= (k-2)) && ((tz/f) > MACHEP)) {
		    tz *= (j - 1)/(z * j);
		    f += tz;
		    j += 2;
		}
		p += f * xsqk/z;
	    }
	    p *= 2.0/PI;
	} else {

	    /* computation for even k */

	    f = 1.0;
	    tz = 1.0;
	    j = 2;

	    while ((j <= (k-2)) && ((tz/f) > MACHEP)) {
		tz *= (j - 1)/(z * j);
		f += tz;
		j += 2;
	    }
	    p = f * x/sqrt(z*rk);
	}

	/* common exit */
	
	if (t < 0) {
	    p = -p;	/* note destruction of relative accuracy */
	}

	p = 0.5 + 0.5 * p;

    } else {
	/* non-integer df */
	z = rk / (rk + t * t);
	p = 0.5 * incbet(0.5*rk, 0.5, z);
	if (t > 0) {
	    p = 1-p;
	} 
    }


    return p;
}