1!
2!     CalculiX - A 3-dimensional finite element program
3!     Copyright (C) 1998-2021 Guido Dhondt
4!
5!     This program is free software; you can redistribute it and/or
6!     modify it under the terms of the GNU General Public License as
7!     published by the Free Software Foundation(version 2);
8!
9!
10!     This program is distributed in the hope that it will be useful,
11!     but WITHOUT ANY WARRANTY; without even the implied warranty of
12!     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13!     GNU General Public License for more details.
14!
15!     You should have received a copy of the GNU General Public License
16!     along with this program; if not, write to the Free Software
17!     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18!
19!     author: Yannick Muller
20!
21      subroutine calc_ider_cross_split(df,pt1,Tt1,xflow1,xflow2,pt2,
22     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
23     &kappa,R,ider,iflag)
24!
25      implicit none
26!
27      integer ichan_num,ider,iflag
28!
29      real*8
30     &df(6),
31     &pt1,
32     &pt2,
33     &Tt1,
34     &Tt2,
35     &xflow1,
36     &xflow2,
37     &A1,
38     &A2,
39     &kappa,
40     &R,
41     &dh1,
42     &dh2,
43     &alpha,
44     &calc_residual_cross_split,
45     &eps,
46     &h,
47     &f0,
48     &zeta_fac,
49     &A_s
50!
51      eps = 1.0e-4
52!
53      f0 = calc_residual_cross_split(pt1,Tt1,xflow1,xflow2,pt2,
54     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
55     &kappa,R,ider,iflag)
56!
57      h = eps*dabs(pt1)
58      if(h.eq.0)then
59         h = eps
60      endif
61      df(1) = (calc_residual_cross_split(pt1+h,Tt1,xflow1,xflow2,pt2,
62     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
63     &kappa,R,ider,iflag)-f0)/h
64!
65      h = eps*dabs(Tt1)
66      if(h.eq.0)then
67         h = eps
68      endif
69      df(2) = (calc_residual_cross_split(pt1,Tt1+h,xflow1,xflow2,pt2,
70     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
71     &kappa,R,ider,iflag)-f0)/h
72!
73      h = eps*dabs(xflow1)
74      if(h.eq.0)then
75         h = eps
76      endif
77      df(3) = (calc_residual_cross_split(pt1,Tt1,xflow1+h,xflow2,pt2,
78     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
79     &kappa,R,ider,iflag)-f0)/h
80!
81      h = eps*dabs(xflow2)
82      if(h.eq.0)then
83         h = eps
84      endif
85      df(4) = (calc_residual_cross_split(pt1,Tt1,xflow1,xflow2+h,pt2,
86     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
87     &kappa,R,ider,iflag)-f0)/h
88!
89      h = eps*dabs(pt2)
90      if(h.eq.0)then
91         h = eps
92      endif
93      df(5) = (calc_residual_cross_split(pt1,Tt1,xflow1,xflow2,pt2+h,
94     &Tt2,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
95     &kappa,R,ider,iflag)-f0)/h
96!
97      h = eps*dabs(Tt2)
98      if(h.eq.0)then
99         h = eps
100      endif
101      df(6) = (calc_residual_cross_split(pt1,Tt1,xflow1,xflow2,pt2,
102     &Tt2+h,ichan_num,A1,A2,A_s,dh1,dh2,alpha,zeta_fac,
103     &kappa,R,ider,iflag)-f0)/h
104!
105      return
106      end
107