1 |
module inifgn_m |
2 |
|
3 |
use dimens_m, only: iim |
4 |
|
5 |
IMPLICIT NONE |
6 |
|
7 |
private iim |
8 |
|
9 |
real sddu(iim), sddv(iim) |
10 |
! sdd[uv] = sqrt(2 pi / iim * (derivative of the longitudinal zoom |
11 |
! function)(rlon[uv])) |
12 |
|
13 |
real unsddu(iim), unsddv(iim) |
14 |
|
15 |
contains |
16 |
|
17 |
SUBROUTINE inifgn(eignval_v, eignfnu, eignfnv) |
18 |
|
19 |
! From LMDZ4/libf/filtrez/inifgn.F, v 1.1.1.1 2004/05/19 12:53:09 |
20 |
|
21 |
! Authors: H. Upadyaya, O. Sharma |
22 |
|
23 |
! Computes the eigenvalues and eigenvectors of the discrete analog |
24 |
! of the second derivative with respect to longitude. |
25 |
|
26 |
use acc_m, only: acc |
27 |
USE dimens_m, ONLY: iim |
28 |
USE dynetat0_m, ONLY: xprimu, xprimv |
29 |
use numer_rec_95, only: jacobi, eigsrt |
30 |
|
31 |
real, intent(out):: eignval_v(:) ! (iim) |
32 |
! eigenvalues sorted in descending order |
33 |
|
34 |
real, intent(out):: eignfnu(:, :), eignfnv(:, :) ! (iim, iim) eigenvectors |
35 |
|
36 |
! Local: |
37 |
|
38 |
REAL delta(iim, iim) ! second derivative, symmetric, elements are angle^{-2} |
39 |
|
40 |
REAL deriv_u(iim, iim), deriv_v(iim, iim) |
41 |
! first derivative at u and v longitudes, elements are angle^{-1} |
42 |
|
43 |
REAL eignval_u(iim) |
44 |
INTEGER i |
45 |
|
46 |
!---------------------------------------------------------------- |
47 |
|
48 |
print *, "Call sequence information: inifgn" |
49 |
|
50 |
sddv = sqrt(xprimv(:iim)) |
51 |
sddu = sqrt(xprimu(:iim)) |
52 |
unsddu = 1. / sddu |
53 |
unsddv = 1. / sddv |
54 |
|
55 |
deriv_u = 0. |
56 |
deriv_u(iim, 1) = unsddu(iim) * unsddv(1) |
57 |
forall (i = 1:iim) deriv_u(i, i) = - unsddu(i) * unsddv(i) |
58 |
forall (i = 1:iim - 1) deriv_u(i, i + 1) = unsddu(i) * unsddv(i + 1) |
59 |
|
60 |
deriv_v = - transpose(deriv_u) |
61 |
|
62 |
delta = matmul(deriv_v, deriv_u) ! second derivative at v longitudes |
63 |
CALL jacobi(delta, eignval_v, eignfnv) |
64 |
CALL acc(eignfnv) |
65 |
CALL eigsrt(eignval_v, eignfnv) |
66 |
|
67 |
delta = matmul(deriv_u, deriv_v) ! second derivative at u longitudes |
68 |
CALL jacobi(delta, eignval_u, eignfnu) |
69 |
CALL acc(eignfnu) |
70 |
CALL eigsrt(eignval_u, eignfnu) |
71 |
|
72 |
END SUBROUTINE inifgn |
73 |
|
74 |
end module inifgn_m |