mcva2.f90

数值计算和数值分析在Fortran下的特殊函数库,是数值计算的必备

MODULE cva2_func
 
! From the book "Computation of Special Functions"
!      by Shanjie Zhang and Jianming Jin
!   Copyright 1996 by John Wiley & Sons, Inc.
! The authors state:
!   "However, we give permission to the reader who purchases this book
!    to incorporate any of these programs into his or her programs
!    provided that the copyright is acknowledged."

! Zhang & Jin's errata applied to subroutine REFINE.
! Latest revision - 5 January 2002
! Corrections by Alan Miller (amiller @ bigpond.net.au)
! Call to subroutine REFINE with last argument = 1; the last argument can
! be changed.

IMPLICIT NONE
INTEGER, PARAMETER  :: dp = SELECTED_REAL_KIND(12, 60)
 
CONTAINS
 

SUBROUTINE cva2(kd, m, q, a)

!       ======================================================
!       Purpose: Calculate a specific characteristic value of
!                Mathieu functions
!       Input :  m  --- Order of Mathieu functions
!                q  --- Parameter of Mathieu functions
!                KD --- Case code
!                       KD=1 for cem(x,q)  ( m = 0,2,4,...)
!                       KD=2 for cem(x,q)  ( m = 1,3,5,...)
!                       KD=3 for sem(x,q)  ( m = 1,3,5,...)
!                       KD=4 for sem(x,q)  ( m = 2,4,6,...)
!       Output:  A  --- Characteristic value
!       Routines called:
!             (1) REFINE for finding accurate characteristic
!                 value using an iteration method
!             (2) CV0 for finding initial characteristic
!                 values using polynomial approximation
!             (3) CVQM for computing initial characteristic
!                 values for q