Fortran90未分類的聲明雖然循環

Question

我想在Fortran90中運行代碼的一小段snipett，並得到一個while語句的未分類的語句錯誤。我在網上查找，無法找到爲什麼這會發生一段時間的聲明。這是我收到的錯誤：

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) 

這裏是我的代碼：

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

我有代碼

while (statement) do 
    code 
enddo 

而不是

identifier: do while (statement 
    code 
end do identifier