Fortran90中用subroutine列主元消去法解方程

以下是使用列主元消去法解方程组的Fortran90代码示例：

subroutine Gauss_elimination(A, b, n)
implicit none
real, dimension(n,n+1) :: A
real, dimension(n) :: b
integer :: n, i, j, k, p
real :: temp

do k = 1, n-1
  p = k
  do i = k+1, n
    if (abs(A(i,k)) > abs(A(p,k))) p = i
  end do

  if (p /= k) then
    do j = k, n+1
      temp = A(k,j)
      A(k,j) = A(p,j)
      A(p,j) = temp
    end do
  end if

  do i = k+1, n
    temp = A(i,k) / A(k,k)
    do j = k+1, n+1
      A(i,j) = A(i,j) - temp * A(k,j)
    end do
  end do
end do

do k = n, 1, -1
  b(k) = A(k,n+1)
  do j = k+1, n
    b(k) = b(k) - A(k,j) * b(j)
  end do
  b(k) = b(k) / A(k,k)
end do

end subroutine Gauss_elimination

在这个例子中，输入矩阵A和向量b以及它们的维度n。该代码将在原地执行列主元消去法，并计算解向量b。注意，此代码假定输入矩阵A是方阵且非奇异的。如果矩阵A不满足这些条件，则必须添加适当的错误检查。