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subroutine fpcyt2(a,n,b,c,nn)
c subroutine fpcyt2 solves a linear n x n system
c a * c = b
c where matrix a is a cyclic tridiagonal matrix, decomposed
c using subroutine fpsyt1.
c ..
c ..scalar arguments..
integer n,nn
c ..array arguments..
real*8 a(nn,6),b(n),c(n)
c ..local scalars..
real*8 cc,sum
integer i,j,j1,n1
c ..
c(1) = b(1)*a(1,4)
sum = c(1)*a(1,5)
n1 = n-1
do 10 i=2,n1
c(i) = (b(i)-a(i,1)*c(i-1))*a(i,4)
sum = sum+c(i)*a(i,5)
10 continue
cc = (b(n)-sum)*a(n,4)
c(n) = cc
c(n1) = c(n1)-cc*a(n1,6)
j = n1
do 20 i=3,n
j1 = j-1
c(j1) = c(j1)-c(j)*a(j1,3)*a(j1,4)-cc*a(j1,6)
j = j1
20 continue
return
end
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