SLATEC Routines --- DBETAI ---

*DECK DBETAI
      DOUBLE PRECISION FUNCTION DBETAI (X, PIN, QIN)
C***BEGIN PROLOGUE  DBETAI
C***PURPOSE  Calculate the incomplete Beta function.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C7F
C***TYPE      DOUBLE PRECISION (BETAI-S, DBETAI-D)
C***KEYWORDS  FNLIB, INCOMPLETE BETA FUNCTION, SPECIAL FUNCTIONS
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C   DBETAI calculates the DOUBLE PRECISION incomplete beta function.
C
C   The incomplete beta function ratio is the probability that a
C   random variable from a beta distribution having parameters PIN and
C   QIN will be less than or equal to X.
C
C     -- Input Arguments -- All arguments are DOUBLE PRECISION.
C   X      upper limit of integration.  X must be in (0,1) inclusive.
C   PIN    first beta distribution parameter.  PIN must be .GT. 0.0.
C   QIN    second beta distribution parameter.  QIN must be .GT. 0.0.
C
C***REFERENCES  Nancy E. Bosten and E. L. Battiste, Remark on Algorithm
C                 179, Communications of the ACM 17, 3 (March 1974),
C                 pp. 156.
C***ROUTINES CALLED  D1MACH, DLBETA, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   770701  DATE WRITTEN
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890911  Removed unnecessary intrinsics.  (WRB)
C   890911  REVISION DATE from Version 3.2
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900315  CALLs to XERROR changed to CALLs to XERMSG.  (THJ)
C   920528  DESCRIPTION and REFERENCES sections revised.  (WRB)
C***END PROLOGUE  DBETAI