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diff --git a/libm/ldouble/btdtrl.c b/libm/ldouble/btdtrl.c
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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 ) );
+}