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/* btdtrl.c
*
* Beta distribution
*
*
*
* SYNOPSIS:
*
* long double a, b, x, y, btdtrl();
*
* y = btdtrl( a, b, x );
*
*
*
* DESCRIPTION:
*
* Returns the area from zero to x under the beta density
* function:
*
*
* x
* - -
* | (a+b) | | a-1 b-1
* P(x) = ---------- | t (1-t) dt
* - - | |
* | (a) | (b) -
* 0
*
*
* The mean value of this distribution is a/(a+b). The variance
* is ab/[(a+b)^2 (a+b+1)].
*
* This function is identical to the incomplete beta integral
* function, incbetl(a, b, x).
*
* The complemented function is
*
* 1 - P(1-x) = incbetl( b, a, x );
*
*
* ACCURACY:
*
* See incbetl.c.
*
*/
/* btdtrl() */
/*
Cephes Math Library Release 2.0: April, 1987
Copyright 1984, 1995 by Stephen L. Moshier
Direct inquiries to 30 Frost Street, Cambridge, MA 02140
*/
#include <math.h>
#ifdef ANSIPROT
extern long double incbetl ( long double, long double, long double );
#else
long double incbetl();
#endif
long double btdtrl( a, b, x )
long double a, b, x;
{
return( incbetl( a, b, x ) );
}
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