1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
subroutine nntc
* (n, r, c, il, jl, ijl, l, d, iu, ju, iju, u, z, b, tmp)
clll. optimize
c*** subroutine nntc
c*** numeric solution of the transpose of a sparse nonsymmetric system
c of linear equations given lu-factorization (compressed pointer
c storage)
c
c
c input variables.. n, r, c, il, jl, ijl, l, d, iu, ju, iju, u, b
c output variables.. z
c
c parameters used internally..
c fia - tmp - temporary vector which gets result of solving ut y = b
c - size = n.
c
c internal variables..
c jmin, jmax - indices of the first and last positions in a row of
c u or l to be used.
c
integer r(1), c(1), il(1), jl(1), ijl(1), iu(1), ju(1), iju(1)
double precision l(1), d(1), u(1), b(1), z(1), tmp(1), tmpk,sum
c
c ****** set tmp to reordered b *************************************
do 1 k=1,n
1 tmp(k) = b(c(k))
c ****** solve ut y = b by forward substitution *******************
do 3 k=1,n
jmin = iu(k)
jmax = iu(k+1) - 1
tmpk = -tmp(k)
if (jmin .gt. jmax) go to 3
mu = iju(k) - jmin
do 2 j=jmin,jmax
2 tmp(ju(mu+j)) = tmp(ju(mu+j)) + tmpk * u(j)
3 continue
c ****** solve lt x = y by back substitution **********************
k = n
do 6 i=1,n
sum = -tmp(k)
jmin = il(k)
jmax = il(k+1) - 1
if (jmin .gt. jmax) go to 5
ml = ijl(k) - jmin
do 4 j=jmin,jmax
4 sum = sum + l(j) * tmp(jl(ml+j))
5 tmp(k) = -sum * d(k)
z(r(k)) = tmp(k)
k = k - 1
6 continue
return
end
|
