SET_GSE_ALGEBRAIC_EQN

Use

Setup utility subroutine for GSE.

Format

Fortran Calling Syntax

SET_GSE_ALGEBRAIC_EQN (gse_id, eqn_idx, errflag)

C/C++ Calling Syntax

c_set_gse_algebraic_eqn (gse_id, eqn_idx, errflag);

Python Calling Syntax

py_set_gse_algebraic_eqn(gse_id, eqn_idx, errflag)

Attributes

gse_id

[integer]

The identifier of the GSE element.

eqn_idx

[integer]

The equation index of the algebraic equations.

Output

errflag

[integer]

Returns information about the call status.

A non-zero value indicates failure.

Comments

1. All indices are 1-based. That is, the index starts from 1, not 0.
2. SET_GSE_ALGEBRAIC_EQN should only be called when iflag=1.
3. In most cases, GSE are in the following form:
   (1)
   
   
   However, in some cases, the state equations may involve both differential and algebraic equations. For example:(2)
   
   

   When this occurs, it is necessary to tell MotionSolve the equation indices of the algebraic equations associated with the algebraic state X₂, using SET_GSE_ ALGEBRAIC_EQN. For example, call: SET_GSE_ALGEBRAIC_EQN (gse_id, 2, errflag)

4. A common use case for SET_GSE_ ALGEBRAIC_EQN is to convert the implicit form of state equations:
   (3)
   
   
   into the explicit form that can be solved in MotionSolve. For example, define:(4)
   
   
   The implicit form can be converted to the following differential algebraic equations:(5)
   
   

   This is in the same DAE form shown in the previous remark.