模块中的意外赋值语句

Question

我想在一个模块中定义一些由多个子例程共享的常量，但是当我尝试编译它时收到很多错误消息（使用 -c 命令）：

错误：MODULE 中出现意外的赋值语句

如果我在子程序中使用相同的代码，它就可以工作。 这是模块的代码：

module rkSetup
!High order embedded Runge-Kutta formulae, by P.J.Prince and J.R.Dormand,
!Journal of Computational and Applied Mathematics, vol. 7, 1981, pages 67-75

    implicit none
    INTEGER, PARAMETER :: dp = SELECTED_REAL_KIND(15)
    integer, parameter :: s = 13 ! number of stages
    integer, parameter :: p = 8 !< Order of the method
    real(dp), dimension(s) :: a !< Runge-Kutta vector of nodes
    real(dp), dimension(s) :: c !< Runge-Kutta vector of weigths
    real(dp), dimension(s) :: d !< Runge-Kutta vector of weigths for high order 
    real(dp), dimension(s,s-1) :: b !< Runge-Kutta matrix

    a = (/0.0_dp, 1.0_dp/18.0_dp, 1.0_dp/12.0_dp, 1.0_dp/8.0_dp, &
        5.0_dp/16.0_dp,3.0_dp/8.0_dp,59.0_dp/400.0_dp,93.0_dp/200.0_dp, &
        5490023248.0_dp/9719169821.0_dp, 13.0_dp/20.0_dp, &
        1201146811.0_dp/1299019798.0_dp, 1.0_dp, 1.0_dp/)

    c = 0.0_dp
    d = 0.0_dp

    d(1) = 14005451.0_dp/335480064.0_dp
    d(6:) = (/-59238493.0_dp/1068277825.0_dp, &
        181606767.0_dp/758867731.0_dp, &
        561292985.0_dp/797845732.0_dp, &
        -1041891430.0_dp/1371343529.0_dp, &
        760417239.0_dp/1151165299.0_dp, &
        118820643.0_dp/751138087.0_dp, &
        -528747749.0_dp/2220607170.0_dp, 1.0_dp/4.0_dp/)

    c(1) = 13451932.0_dp/455176623.0_dp
    c(6:12) = (/-808719846.0_dp/976000145.0_dp, &
        1757004468.0_dp/5645159321.0_dp, &
        656045339.0_dp/265891186.0_dp, &
        -3867574721.0_dp/1518517206.0_dp, &
        465885868.0_dp/322736535.0_dp, &
        53011238.0_dp/667516719.0_dp, 2.0_dp/45.0_dp/)

    b = 0.0_dp

    b(:,1) = (/0.0_dp, 1.0_dp/18.0_dp, 1.0_dp/48.0_dp, &
        1.0_dp/32.0_dp, 5.0_dp/16.0_dp, 3.0_dp/80.0_dp, &
        29443841.0_dp/614563906.0_dp, 16016141.0_dp/946692911.0_dp, &
        39632708.0_dp/573591083.0_dp, 246121993.0_dp/1340847787.0_dp, &
        -1028468189.0_dp/846180014.0_dp, 185892177.0_dp/718116043.0_dp, &
        403863854.0_dp/491063109.0_dp/)
    b(3,2) = 1.0_dp/16.0_dp
    b(4:5,3) = (/3.0_dp/32.0_dp, -75.0_dp/64.0_dp /)
    b(5:,4) = (/75.0_dp/64.0_dp,3.0_dp/16.0_dp, &
        77736538.0_dp/692538347.0_dp, 61564180.0_dp/158732637.0_dp, &
        -433636366.0_dp/683701615.0_dp, -37695042795.0_dp/15268766246.0_dp, &
        8478235783.0_dp/508512852.0_dp, -3185094517.0_dp/667107341.0_dp, &
        -5068492393.0_dp/434740067.0_dp/)
    b(6:,5) = (/3.0_dp/20.0_dp, -28693883.0_dp/1125000000.0_dp, &
        22789713.0_dp/633445777.0_dp, -421739975.0_dp/2616292301.0_dp, &
        -309121744.0_dp/1061227803.0_dp, 1311729495.0_dp/1432422823.0_dp, &
        -477755414.0_dp/1098053517.0_dp, -411421997.0_dp/543043805.0_dp/)
    b(7:,6) = (/23124283.0_dp/1800000000.0_dp, &
        545815736.0_dp/2771057229.0_dp,100302831.0_dp/723423059.0_dp, &
        -12992083.0_dp/490766935.0_dp,-10304129995.0_dp/1701304382.0_dp, &
        -703635378.0_dp/230739211.0_dp,652783627.0_dp/914296604.0_dp/)
    b(8:,7) = (/-180193667.0_dp/1043307555.0_dp, &
        790204164.0_dp/839813087.0_dp, 6005943493.0_dp/2108947869.0_dp, &
        -48777925059.0_dp/3047939560.0_dp, 5731566787.0_dp/1027545527.0_dp, &
        11173962825.0_dp/925320556.0_dp/)
    b(9:,8) = (/800635310.0_dp/3783071287.0_dp, &
        393006217.0_dp/1396673457.0_dp, 15336726248.0_dp/1032824649.0_dp, &
        5232866602.0_dp/850066563.0_dp, -13158990841.0_dp/6184727034.0_dp /)
    b(10:,9) = (/123872331.0_dp/1001029789.0_dp, &
        -45442868181.0_dp/3398467696.0_dp,-4093664535.0_dp/808688257.0_dp, &
        3936647629.0_dp/1978049680.0_dp/)
    b(11:,10) = (/3065993473.0_dp/597172653.0_dp, &
        3962137247.0_dp/1805957418.0_dp, -160528059.0_dp/685178525.0_dp/)
    b(12:,11) = (/65686358.0_dp/487910083.0_dp, &
        248638103.0_dp/1413531060.0_dp/)

end module rkSetup

我该如何解决这个问题？

Answer 1

根据Fortran 2008 Standard 中的表2.2，您不能将可执行语句直接放入模块中。

如果你想初始化这个数据，要么（a）在声明期间进行，要么（b）添加一个你可以调用的专用子程序来进行初始化。

(a)

real(dp), dimension(s),parameter :: a = &
    (/0.0_dp, 1.0_dp/18.0_dp, 1.0_dp/12.0_dp, 1.0_dp/8.0_dp, &
    5.0_dp/16.0_dp,3.0_dp/8.0_dp,59.0_dp/400.0_dp,93.0_dp/200.0_dp, &
    5490023248.0_dp/9719169821.0_dp, 13.0_dp/20.0_dp, &
    1201146811.0_dp/1299019798.0_dp, 1.0_dp, 1.0_dp/)

(b)

module rkSetup
!High order embedded Runge-Kutta formulae, by P.J.Prince and J.R.Dormand,
!Journal of Computational and Applied Mathematics, vol. 7, 1981, pages 67-75

    implicit none
    INTEGER, PARAMETER :: dp = SELECTED_REAL_KIND(15)
    !...
    contains
    subroutine init()
        a = (/0.0_dp, 1.0_dp/18.0_dp, 1.0_dp/12.0_dp, 1.0_dp/8.0_dp, &
            5.0_dp/16.0_dp,3.0_dp/8.0_dp,59.0_dp/400.0_dp,93.0_dp/200.0_dp, &
            5490023248.0_dp/9719169821.0_dp, 13.0_dp/20.0_dp, &
            1201146811.0_dp/1299019798.0_dp, 1.0_dp, 1.0_dp/)
        !....
    end subroutine
end module

Answer 2

Alexander Vogt 是正确的，您可以在初始化例程中定义它们。但是，如果a,b,c,d 是常量，最有效的做法是将它们定义为参数。这是执行此操作的两种方法的示例：

module params
   implicit none

   integer, parameter :: s = 5

   ! -- Initialization method 1
   real, parameter :: a(s) = (/ 1.2, 3.4, &
      5.6, 7.8, 9.0 /)

   ! -- Initialization method 2
   real :: b(s)
   parameter( b = (/ 1.2, 3.4, &
      5.6, 7.8, 9.0 /) )

end module params

program main
   use params
   write(*,'(a,5f6.2)') 'a is: ', a
   write(*,'(a,5f6.2)') 'b is: ', b
end program main

如果您希望设置多维的大型参数数组，请考虑使用reshape。