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MODULE sor_module


MODULE sor_module
USE jacobi_module

TYPE oddeven
REAL(real8), DIMENSION(:,:), POINTER :: odd
REAL(real8), DIMENSION(:,:), POINTER :: even
END TYPE oddeven

TYPE redblack
TYPE (oddeven) :: red, black
END TYPE redblack

REAL(real8), PARAMETER :: pi=3.141593d0
REAL(real8) :: omega, rhoj, rhojsq, delr, delb

CONTAINS

FUNCTION news(v, m, mp, i, j)
INTEGER :: m, mp, i, j
REAL(real8), DIMENSION(0:m+1,0:mp+1), TARGET :: v
TYPE (redblack) :: news
news%black%odd => v(i+1:i+m:2,j+2:j+mp:2)
news%black%even => v(i+2:i+m:2,j+1:j+mp:2)
news%red%odd => v(i+1:i+m:2,j+1:j+mp:2)
news%red%even => v(i+2:i+m:2,j+2:j+mp:2)
END FUNCTION news

SUBROUTINE update_u(c, n, e, w, s, vnew, m, mp, omega, del)
IMPLICIT NONE
INTEGER m, mp
REAL(real8) :: omega, del
REAL(real8), DIMENSION(1:m/2,1:mp/2) :: vnew
TYPE (oddeven) :: c, n, e, w, s
vnew = (n%odd + e%odd + w%odd + s%odd )*0.25d0
c%odd = (1.0d0 - omega)*c%odd + omega*vnew
del = sum(dabs(vnew-c%odd))
vnew = (n%even + e%even + w%even + s%even)*0.25d0
c%even = (1.0d0 - omega)*c%even + omega*vnew
del = del + sum(dabs(vnew-c%even))
END SUBROUTINE update_u
END MODULE sor_module