意外的賦值語句

Question

我想一個模塊內定義由幾個子程序共享的一些常量，但我得到許多錯誤消息，當我嘗試編譯它（使用-c命令）：

Error: Unexpected assignment statement in MODULE

如果我在子程序中使用相同的代碼，它就可以工作。 這裏的模塊代碼：

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 

我怎樣才能解決這個問題？

Answer 1

根據Fortran 2008 Standard中的表2.2，您不能直接將可執行語句放置到模塊中。

如果要初始化此數據，請（a）在聲明期間執行此操作，或者（b）添加可調用的專用子例程以執行初始化。

（一）

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

亞歷山大·沃格特是正確的，你可以在初始化程序定義它們。但是，如果a,b,c,d是常量，最有效的方法是將它們定義爲參數。下面是兩種方法可以做到這一點的例子：

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 

如果你想設置一個較大的參數數組與一個維以上，可以考慮使用reshape。