scifunc_block_m

Block Screenshot

Contents

• Description

• Parameters

• User-defined functions

• Interfacing function

• Computational function

• Example

Description

This block can realize any type of Scicos block. The function of the block is defined interactively using dialogue boxes and in Scilab language. During simulation, these instructions are interpreted by Scilab; the simulation of diagrams that include these types of blocks is slower.

Arguments

• input ports sizes

  a matrix. Number of regular input ports

  Properties : Type 'mat' of size [-1 2]

  Example : [1,1] for one input of size 1x1; [1,1;2,3] for two inputs of size 1x1 and 2x3

• output port sizes

  a matrix. Number of regular output ports

  Properties : Type 'mat' of size [-2 2]

  Example : [1,1] for one output of size 1x1; [1,1;2,3] for two outputs of size 1x1 and 2x3

• input event ports sizes

  a column vector. Number of input event ports

  Properties : Type 'vec' of size -1

  Example : [1] for one input event port; [1;1] for two input event ports

• output events ports sizes

  a column vector. Number of output event ports

  Properties : Type 'vec' of size -1

  Example : [1] for one output event port; [1;1] for two output event ports

• initial continuous state

  a column vector.

  Properties : Type 'vec' of size -1

  Example : [0;0] for two initial continuous states

• initial discrete state

  a column vector.

  Properties : Type 'vec' of size -1

  Example : [0;0] for two initial discrete states

• System parameters vector

  a column vector.

  Properties : Type 'vec' of size -1

  Example : [0.5;1.5;2.5] for three parameters

• initial firing vector

  a column vector. Size of this vector corresponds to the number of event outputs. The value of the i-th entry specifies the time of the preprogrammed event firing on the i-th output event port. If less than zero, no event is preprogrammed.

  Properties : Type 'vec' of size sum(Number of output event ports)

  Example : [1;2] 1 and 2 are the preprogrammed events firing that correspond to the first output event port and to the second output event port respectively

• is block always active

  Properties : Type 'vec' of size 1

  Example : 1 the block is always active; 0 the block is not always active

• Other dialogues are opened consecutively where the user may write Scilab code associated with the computations needed (block initialization, outputs, continuous and discrete state, output events date, block ending).

User-defined functions

The behavior of the Scilab function block is defined by user-written Scilab instructions. Each instruction set must be defined depending on the block configuration (and should match their count and size). The variables used are:

y1, y2, ..., yN

the values of the output signals

t

the current time

x

the continuous state

xd

the continuous derivative

z

the discrete state

u1, u2, ..., uM

the input signals

n_evi

the event triggering the computation

t_evo

the next time events

rpar

the real parameters

Compute the output

If the block output values, the user should define : y1, y2, ..., yN

from t, x, z, u1, u2, ..., uM, n_evi, rpar variables.

This is the most common instructions to define and they will be called at each time step.

Compute the continuous state derivative

If the block has continuous state, the user should define: xd

from t, x, z, u1, u2, ..., uM, rpar variables.

The instructions will be for derivative evaluation in case of continuous state.

Compute the state values

If the block has continuous or discrete state, the user should define: x, z

from t, x, z, u1, u2, ..., uM, n_evi, rpar variables.

The instructions will update the internal state of the block.

Setup next event time

If the block generate events, the user should define : t_evo

from t, x, z, u1, u2, ..., uM, n_evi, rpar variables.

The instructions will setup the next event times on the corresponding output event port.

Re-initialize states

If the block has states, the user should define : x, z

from x, z, rpar variables.

The instructions will be called at the beginning of the simulation to initialize the states.

Final values

The user can define: x, z

from x, z, rpar variables.

At the end of the simulation this will compute final state values.

Imposing constraints

The user can define : y1, y2, ..., yN

from x, z, u1, u2, ..., uM, n_evi, rpar variables.

At the start of the simulation the instructions may be called multiple times to compute constraints.

Example

Interfacing function

• SCI/modules/scicos_blocks/macros/Misc/scifunc_block_m.sci

Computational function

• SCI/modules/scicos/src/fortran/scifunc.f (Type 3)