SLATEC Routines --- BESI1 ---

*DECK BESI1
      FUNCTION BESI1 (X)
C***BEGIN PROLOGUE  BESI1
C***PURPOSE  Compute the modified (hyperbolic) Bessel function of the
C            first kind of order one.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C10B1
C***TYPE      SINGLE PRECISION (BESI1-S, DBESI1-D)
C***KEYWORDS  FIRST KIND, FNLIB, HYPERBOLIC BESSEL FUNCTION,
C             MODIFIED BESSEL FUNCTION, ORDER ONE, SPECIAL FUNCTIONS
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C BESI1(X) calculates the modified (hyperbolic) Bessel function
C of the first kind of order one for real argument X.
C
C Series for BI1        on the interval  0.          to  9.00000D+00
C                                        with weighted error   2.40E-17
C                                         log weighted error  16.62
C                               significant figures required  16.23
C                                    decimal places required  17.14
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  BESI1E, CSEVL, INITS, R1MACH, XERMSG
C***REVISION HISTORY  (YYMMDD)
C   770401  DATE WRITTEN
C   890531  Changed all specific intrinsics to generic.  (WRB)
C   890531  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   900326  Removed duplicate information from DESCRIPTION section.
C           (WRB)
C***END PROLOGUE  BESI1