追赶法解三对角矩阵fortran
时间: 2023-06-29 15:16:33 浏览: 182
以下是用追赶法解三对角矩阵的 Fortran 代码:
```
SUBROUTINE tridiagonal_solver(N, A, B, C, R, X)
! Solve the tridiagonal system Ax = R using the Thomas algorithm
! where A, B, and C are the diagonal and off-diagonal elements of a tridiagonal matrix
! N is the number of unknowns, R is the right-hand side, and X is the solution vector
IMPLICIT NONE
INTEGER, INTENT(IN) :: N
REAL, DIMENSION(N), INTENT(IN) :: A, B, C, R
REAL, DIMENSION(N), INTENT(OUT) :: X
REAL :: M(N) ! temporary storage
INTEGER :: I
! Forward elimination
M(1) = B(1) / A(1)
DO I = 2, N-1
M(I) = B(I) / (A(I) - M(I-1) * C(I-1))
END DO
! Back substitution
X(N) = (R(N) - C(N-1) * X(N-1)) / (A(N) - C(N-1) * M(N-1))
DO I = N-1, 1, -1
X(I) = M(I) * X(I+1) + (R(I) - C(I) * X(I+1)) / A(I)
END DO
END SUBROUTINE tridiagonal_solver
```
这个代码使用了 Thomas 算法,也被称为追赶法。它是一种用于解三对角线性方程组的快速算法,具有良好的稳定性和可靠性。在这个代码中,首先进行了前向消元,然后进行了回带代入,最终得到了方程组的解X。