Index-1 DAE block
The Algebraic-differential Constraint block constrains the input signal f(x',x) to zero and outputs an algebraic state x and a derivative of the state x'. The block outputs the value necessary to produce a zero at the input. The output must affect the input through some direct feedback path, i.e., the feedback path should only contains blocks with direct feedthrough (without internal states). This enables the user to specify equations for fully implicit index-1 differential/algebraic systems (DAEs), i.e., F(x',x)=0.
By default, the initial values of the state vector and the derivative of the state vector which is used as initial guess values are zero. If the solver cannot converge towards the solution at the beginning of the integration, the user can help the solver by providing an initial guess that is close to the solution value. If f(x',x) has several solutions, the initial guess helps the solver to select the desired solution.
- Initial guess values of states x
Initial value of the states used as initial guess to help the solver to converge toward the desired solution.
Properties : Type 'vec' of size -1.
- Initial guess values of derivative x'
Initial guess value of the derivatives of states used as initial guess to help the solver to converge toward the desired solution specially at the beginning of the simulation.
Properties : Type 'vec' of size -1.
- Id(i)=1: if x'(i) is present in the feedback, else Id(i)=0
The elemenets of this vector indicate if the derivative of the corresponding state has been used in the feedback path, i.e., if it exists in the function f(x',x)=0.
Properties : Type 'vec' of size -1.
- always active: yes
- direct-feedthrough: no
- zero-crossing: no
- mode: no
- regular inputs:
- port 1 : size [1,1] / type 1
- regular outputs:
- port 1 : size [1,1] / type 1
- port 2 : size [1,1] / type 1
- number/sizes of activation inputs: 0
- number/sizes of activation outputs: 0
- continuous-time state: yes
- discrete-time state: no
- object discrete-time state: no
- name of computational function: constraint_c
- SCI/macros/scicos_blocks/Misc/CONSTRAINT2_c.sci [view code]
- SCI/routines/scicos/constraint_c.c (Type 10004) [view code]
Masoud Najafi INRIA
