Subroutine Type

Modeling

Definition

Used to calculate a differential equation value for a control DIFF entity.

Use

A control diff statement based on a user-defined differential equation:

<Control_Diff

    label               = "Diff/301001"

    id                  = "301001"

    is_implicit         = "FALSE"

    ic                  = "0."

    ic_dot              = "0."

    is_static_hold      = "FALSE"

    type                = "USERSUB"

    usrsub_param_string = "USER(30102020,30101010)"

    usrsub_dll_name     = "NULL"

 />

Calling Syntax

Fortran

SUBROUTINE DIFSUB (ID, TIME, PAR, NPAR, DFLAG, IFLAG, VALUE)

C

void STDCALL DIFSUB (int *id, double *time, double *par, int *npar, int *dflag, int *iflag, double *value)

Python

def DIFSUB(id, time, par, npar, dflag, iflag):

    return value

MATLAB

function value = DIFSUB(id, time, par, npar, dflag, iflag)

Input Arguments

[integer] ID

The differential equation element identifier.

[double precision] TIME

The current simulation time.

[double precision] PAR

An array that contains the constant arguments from the list provided in the user-defined statement.

[integer] NPAR

The number of entries in the PAR array.

[logical] DFLAG

The differencing flag set to true when the solver evaluates the partial derivatives.

[logical] IFLAG

The initialization flag.

Output Values

[double precision] VALUE

The double precision value that contains the value of the differential equation.

Example

def DIFSUB(id, time, par, npar, dflag, iflag):

    ipar = 2*[0]

    ipar[0] = int(par[0])

    ipar[1] = int(par[1])

    [dz, errflg] = py_sysfnc("DZ", ipar)

    py_errmes(errflg, "Error calling SYSFNC for DZ", id, "STOP")

    ipar = 1*[0]

    ipar[0] = id

    [dif, errflg] = py_sysfnc("DIF", ipar)

    py_errmes(errflg, "Error calling SYSFNC for DIF", id, "STOP")

    value = dz-dif

    return value