Mathematical expression
The Expression block applies the specified Scilab expressions to its input.
number of inputs
Block input can be a scalar or vector.
Properties : Type 'vec' of size 1
scilab expression
The Scilab expression applied to the input.
Properties : Type 'vec' of size 1
All Scilab operators are supported.
Only a restricted list of functions are supported in the expression.
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![]() | In the provided expression, any subexpression being an exponent more than
1-character long must end with a space, to be correctly displayed on the
block's icon.
This constrain has no consequence on the computational validity of the expression.
Examples: "u1^12-u2", "u1^ 12-u2", "u1^abc - 3", "u1^(u2-3) + 4" will be
correctly displayed, while "u1^abc-3" would be displayed as "u1^{abc-3}"
(but well computed as u1^abc + 3 )
and "u1^(u2-3)+4" as "u1^{(u2-3)+4}" instead of "u1^{(u2-3)} + 4".
"u1^abc - 3" and "u1^(u2-3) + 4" will have to be entered instead. |
use zero-crossing
Select to enable zero crossing detection.
Properties : Type 'vec' of size 1
always active: no
direct-feedthrough: yes
zero-crossing: yes
mode: yes
regular inputs:
- port 1 : size [1,1] / type 1
- port 2 : size [1,1] / type 1
regular outputs:
- port 1 : size [1,1] / type 1
number/sizes of activation inputs: 0
number/sizes of activation outputs: 0
continuous-time state: no
discrete-time state: no
object discrete-time state: no
name of computational function: evaluate_expr
The following example calculate an arbitrary expression with multiple different configuration or blocks.
y = u(1) - u(2) - u(3)
SCI/modules/scicos_blocks/macros/Misc/EXPRESSION.sci