SUBROUTINE VJ1 (M, X, F, WORK, IWORK, INFO) C***BEGIN PROLOGUE VJ1 C***PURPOSE Computes the Bessel function of the first kind C of order one (J1) for a vector of real arguments C***LIBRARY VFNLIB C***CATEGORY C10B1 C***TYPE SINGLE PRECISION (VJ1-S, DVJ1-D) C***KEYWORDS BESSEL FUNCTION, FIRST KIND, SPECIAL FUNCTION, C ORDER ONE, VECTORIZED C***AUTHOR SAUNDERS, B. V., (NIST) C COMPUTING AND APPLIED MATHEMATICS LABORATORY C NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY C GAITHERSBURG, MD 20899 C BOISVERT, R. F., (NIST) C COMPUTING AND APPLIED MATHEMATICS LABORATORY C NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY C GAITHERSBURG, MD 20899 C***DESCRIPTION C C VJ1 computes the Bessel function of the first kind of order C one (J1) for real arguments using uniform approximation by C Chebyshev polynomials. C C C P A R A M E T E R S C C M (Input) Integer (M .GT. 0) C The number of arguments at which the function is to be C evaluated. C C X (Input) Real array of length M C The arguments at which the function is to be evaluated are C stored in X(1) to X(M) in any order. C C F (Output) Real array of length M C F(i) contains the value of the function at X(i), i=1,..,M. C C WORK (Work) Real vector of length 7*M C C IWORK (Work) Integer vector of length M C C C INFO (Output) Integer C Indicates status of computed result. The following table C lists possible values and their meanings. If OK=Yes then C all F(i) have been set, otherwise none have been set. C C INFO OK Description C ------------------------------------------------------------ C -1 Yes Warning: Some abs(X(i)) so small J1 underflows. C The corresponding F(i) are set to zero. C 0 Yes Successfull execution. C 1 No Error: M .LE. 0 C 2 No Error: Some abs(X(i)) so big that no precision C possible in computing J1. The index of the C first offending argument is returned in IWORK(1). C C ********************************************************************* C This routine is a modification of the function BESJ1 developed by C W. Fullerton of LANL. C ********************************************************************* C C***REFERENCES (NONE) C***ROUTINES CALLED WJ1 C***REVISION HISTORY (YYMMDD) C 910226 DATE WRITTEN