Random

Uniformly distributed random numbers.

Collaboration diagram for Random:

Generates random numbers, uniformly distributed between RandomMin and RandomMax. The user must specify the type of random (constant or variable).

A VariableRandom draws a new number on every accepted step and holds it until the next one, so the output is the same for every integrator and for every evaluation inside a step (Runge-Kutta stages and finite-difference Jacobian columns). OutDot is 0. A ConstRandom draws once. The numbers come from std::mt19937 seeded with Seed: the same Seed gives the same numbers on every run and platform. Give each Src/Random its own Seed when the signals must differ (owner ruling D23).

An example of a time variable random number generator.

Author

Benjamin Scholz

Date

11.09.2007 BSC: Initial version.

19.07.2011 KGA: Updated to FhSim 2.0 and documented

29.10.2026 Uniform, seeded, drawn on accepted steps (D23).

<Lib
  LibName     = "fhsim_base"
  SimObject   = "Src/Random"
  Name        = "random"
  RandomType  = "VariableRandom"
  RandomMin   = "0.2"
  RandomMax   = "0.8"
  Seed        = "3"
/>

Input Ports

This function has no inputs.

Output Ports

Name	Width	Description
Out	<PortWidth>	The output signal
OutDot	<PortWidth>	The derivative of the output signal

Configuration parameters

Name	Width	Description
PortWidth		The number of elements in the signal.
RandomType	1	A bool variable define the type of random function. Choose a constant random number or a variable random number. The variable must be defined as <ConstRandom> or <VariableRandom>.
RandomMin	<PortWidth>	The lower limit for the random numbers.
RandomMax	<PortWidth>	The upper limit for the random numbers.
Seed	1	Seed of the random number generator. Default 1, so a run is repeatable.

Initial conditions

There are no initial conditions for this function.

Full example file

<Contents>
  <OBJECTS>
    <Lib
        LibName="base"
        SimObject="Src/Random"
        Name="RandCons"
        RandomType="ConstRandom"
        RandomMin="-10"
        RandomMax="3"
      />
      <Lib
        LibName="base"
        SimObject="Src/Random"
        Name="RandVar"
        RandomType="VariableRandom"
        RandomMin="0"
        RandomMax="7"
      />
    </OBJECTS>
 
  <INTERCONNECTIONS>
    <Connection
    />
  </INTERCONNECTIONS>
 
  <INITIALIZATION>
    <InitialCondition
    />
  </INITIALIZATION>
 
  <SIMULATION>
    <Timing TStart="0" TEnd="31"/>
    <Integrator Method="RK45_i" NumCores="1" LogStates="1" UseRSSNorm="0">
      <StepControl StepMax="0.002" StepMin="0.00000001" AbsTol="1e-3" RelTol="1e-3"/>
    </Integrator>
    
  </SIMULATION>
 
<OBSERVERS>
    <FileOutput TOutput="0, 0,1,2,3, 31" Select="objects:all"/>
  </OBSERVERS>
</Contents>

This SimObject is referred to as Src/Random