Session 9: Symbolic variables
and Context
To set block parameters, any Scilab variable or expression can be used.
The only constraint is that the variables de defined in the current environment
when used. These variables can be defined in the Context of the diagram.
Construct the following diagram
The u^3 block computes the third
power of the input; 3 is a block parameter
Define the context of the diagram
as follows
Context
in the Edit
menu should be used to open the context
of the diagram.
The variables alph and beta
are now defined and can be used as parameter
Set Constant
block parameter to alph
and the Power block
parameter to beta
The parameter of the Constant
block for example should be set as follows
This parameter is stored symbolically
The diagram after parameter changes looks like
The values of alph and beta
are defined in the Context
To change the value of these parameters, it is enough to update the Context.
Symbolic definition is particularly useful
when the same variable is used in more than one place in the diagram. Changing
the value of this variable in the Context changes
the parameter values of all the blocks in which this variable used.
Every Super Block has a Context of its
own. A variable defined in the Context of
a diagram can be used to set block parameters of the blocks in the diagram.
Even if a variable is not defined in the Context
of the Super Block, it can be used if it is defined in the Context
of the diagram containing the Super Block, or in the Context
of the Super Block containing the Super Block containing the Super
Block, and so on. In case of multiple defintion, the value is the value
defined in the Context closet to the diagram.
Here ends the tutorial.
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