compiler-errors - Fortran90 未分类语句 While 循环

Question

我试图让一小段代码在 Fortran90 中运行，但我得到了一个带有 while 语句的未分类语句错误。我在网上查看过，找不到为什么会在 while 语句中发生这种情况。这是我得到的错误：

Test.f90:11.4:

    while (R < MinimumEnergy) do
    1
Error: Unclassifiable statement at (1)
Test.f90:15.8:

        while (f < R) do
        1
Error: Unclassifiable statement at (1)
Test.f90:19.11:

        enddo
           1
Error: Expecting END PROGRAM statement at (1)
Test.f90:23.7:

    enddo
       1
Error: Expecting END PROGRAM statement at (1)

这是我的代码：

program FD_Number
      REAL :: MinimumEnergy = 4.5;
      REAL :: a = -9;
      REAL :: b = 9;
      REAL R, randomN, f

      REAL :: FD
            FD(R) = (1 + exp(R))**(-1)
      R = 0;

    while (R < MinimumEnergy) do
        R = 999999;
        f = FD(a + (b - a)*R);

        while (f < R) do
            call random_number(randomN)
            f = FD(a + (b - a)*randomN);
            call random_number(R)
        enddo

        R = a + (b - a)*R;
        f = FD(R);
    enddo

    print *, f
end

Answer 1

我有代码

while (statement) do
  code
enddo

而不是

identifier: do while (statement)
  code
end do identifier