User-Defined Expression
Description
User-Defined Expression
This control block allows the user to write any mathematical expression that are evaluated at every time-step/iterations. Variables named "i1","i2"..."in" can be used to represent model inputs.
Example of supported expressions:
- sin(2*i1)
- max(i1, i2)
- sqrt(i1ˆ2 + i2ˆ2)
This device should be used for "continuous" variables only. SIMBA will not consider discontinuities generated by user-defined expressions as such and therefore will not reduce the time steps. For example, it should not be used in place of a comparator controlling a switch.
The tables below present the list of functions and operators supported by this model.
| Function name | Description | Example |
|---|---|---|
| abs | absolute value | abs(i1) |
| acos | arcus cosine | acos(i1) |
| acosh | hyperbolic arcus cosine | acosh(i1) |
| asin | arcus sine | asin(i1) |
| asinh | hyperbolic arcus sine | asinh(i1) |
| atan | arcus tangent | atan(i1) |
| atanh | hyperbolic arcus tangent | atanh(i1) |
| atan2 | 2-arguments arcus tangent | atan2(i1, i2) where i1 is y-coordinate, i2 is x-coordinate |
| avg | average value | avg(i1,i2,...) |
| cos | cosine | cos(i1) |
| cosh | hyperbolic cosine | cosh(i1) |
| exp | exponential function | exp(i1) |
| ln | natural logarithm | ln(i1) |
| log | natural logarithm | log(i1) |
| log2 | 2-base logarithm | log2(i1) |
| log10 | 10-base logarithm | log10(i1) |
| max | maximal value | max(i1,i2,...) |
| min | minimal value | min(i1,i2,...) |
| rint | round to nearest interger | rint(i1) |
| sign | sign of the number (1 or -1) | sign(i1) |
| sin | sine | sin(i1) |
| sinh | hyperbolic sine | sinh(i1) |
| sqrt | square root value | sqrt(i1) |
| sum | sum of all arguments | sum(i1,i2,...) |
| tan | tangent | tan(i1) |
| tanh | hyperbolic tangent | tanh(i1) |
| Operator | Description | Example |
|---|---|---|
| + | addition | i1+i2 |
| - | subtraction | i1-i2 |
| * | multiplication | i1*i2 |
| / | division | i1/i2 |
| ^ | raise to the power | i1^i2 |
| ?: | conditional (ternary) operator | i1 >= 0 ? 3 : 2 |
| Variable | Description |
|---|---|
| time | current simulation time |
| dt | current time step |
Library
Control > Math
Parameters
| Property | Display Name | Parameter Type | Description |
|---|---|---|---|
| Expression | Expression | StringParameter | Mathematical expression |
| NumberOfInputs | Number of Inputs | IntParameter | Number of Inputs |
| SamplingTime | Sampling Time [s] | DoubleParameter | Sampling Time |
Pins
| Property | Pin Name | Type | Description |
|---|---|---|---|
| i1 | i1 | ControlIn | Input 0 |
| Out | Out | ControlOut | Output |
Default Size
| Width | Height |
|---|---|
| 8 | 4 |