************80
! ENVJ is a utility function used by MSTA1 and MSTA2.
Licensing:
This routine is copyrighted by Shanjie Zhang and Jianming Jin. However,
they give permission to incorporate this routine into a user program
provided that the copyright is acknowledged.
Modified:
14 March 2012
Author:
Shanjie Zhang, Jianming Jin
Reference:
Shanjie Zhang, Jianming Jin,
Computation of Special Functions,
Wiley, 1996,
ISBN: 0-471-11963-6,
LC: QA351.C45.
Parameters:
Input, integer ( kind = 4 ) N, ?
Input, real ( kind = 8 ) X, ?
Output, real ( kind = 8 ) ENVJ, ?
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
integer(kind=4) | :: | n | ||||
real(kind=8) | :: | x |
function envj ( n, x ) !*****************************************************************************80 ! !! ENVJ is a utility function used by MSTA1 and MSTA2. ! ! Licensing: ! ! This routine is copyrighted by Shanjie Zhang and Jianming Jin. However, ! they give permission to incorporate this routine into a user program ! provided that the copyright is acknowledged. ! ! Modified: ! ! 14 March 2012 ! ! Author: ! ! Shanjie Zhang, Jianming Jin ! ! Reference: ! ! Shanjie Zhang, Jianming Jin, ! Computation of Special Functions, ! Wiley, 1996, ! ISBN: 0-471-11963-6, ! LC: QA351.C45. ! ! Parameters: ! ! Input, integer ( kind = 4 ) N, ? ! ! Input, real ( kind = 8 ) X, ? ! ! Output, real ( kind = 8 ) ENVJ, ? ! implicit none real ( kind = 8 ) envj integer ( kind = 4 ) n real ( kind = 8 ) x envj = 0.5D+00 * log10 ( 6.28D+00 * n ) - n * log10 ( 1.36D+00 * x / n ) return end function envj