Solves differential algebraic equations (DAEs) with initial conditions by using the Radau IIA method. You must manually select the polymorphic instance to use.


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Inputs/Outputs

  • ccclst.png DAE F(X,X',t) —

    DAE (F,X',t) is a cluster of formula strings and variable strings that implements differential algebraic equations (DAEs).

    For this VI, F(X,X',t)=0.

  • c1dstr.png F(X,X',t) —

    F(X,X',t) is an array of strings specifying the DAEs. The specified formulas can contain any number of valid variables.

  • c1dstr.png X —

    X is an array of strings that specify the variables of the initial state.

  • c1dstr.png X' —

    X' is an array of strings that specify the variables of derivatives of the initial state. The length of X must be equal to the length of X'.

  • cstr.png time —

  • c1ddbl.png Initial Values —

    Initial Values specify the values of the initial state of the VI.

  • c1ddbl.png Initial Derivatives —

    Initial Derivatives specify the values of the initial state derivative. The length of the Initial Derivative must equal the length of the Initial Values.

  • ccclst.png simulation parameters —

    simulation parameters specifies the set of parameters used to configure the differential algebraic equation (DAE) solver.

  • cdbl.png initial time —

    initial time specifies the time at which to start the DAE solver. The default is 0.

  • cdbl.png final time —

    final time is the time at which the DAE solver stops. The final time must be larger than the initial time. The default value is 10.

  • c1ddbl.png Absolute Tolerance —

    Absolute Tolerance specifies the absolute tolerance the DAE solver uses to control the local error for each variable. You can specify either a scalar tolerance which applies to all variables, or an array of tolerance which applies to each variable respectively. The Absolute Tolerance cannot be negative. The corresponding Absolute Tolerance and Relative Tolerance cannot both be zeroes. The default is 0.001.

    The DAE solver calculates the local error by the following equation: |X|*relative tolerance + absolute tolerance

    LabVIEW uses this error to adjust the step size. If the error is too large, the DAE solver rejects the current step and reduces the step size for another try. If the error is too small, the DAE solver accepts the current step and increases the step size for next try. The Absolute Tolerance is most significant when X is small.

  • c1ddbl.png Relative Tolerance —

    Relative Tolerance specifies the relative tolerance the DAE solver uses to control the local error for each variable state. You can specify either a scalar tolerance which applies to all variables or an array of tolerance which applies to each variable respectively. The Relative Tolerance cannot be negative. The Absolute Tolerance and Relative Tolerance cannot both be zeroes. The default is 0.001.

    The DAE solver calculates the local error by the following equation: |X|*relative tolerance + absolute tolerance

    LabVIEW uses this error to adjust the step size. If the error is too large, the solver rejects the current step and reduces the step size for another try. If the error is too small, the solver accepts the current step and increases the step size for next try. The Relative Tolerance is most significant when X is large.

  • cdbl.png minimum time step —

    minimum time step specifies the smallest time step size the DAE solver can use to evaluate the state. The minimum time step must be larger than 0. The default value is 1 E-8.

  • cdbl.png maximum time step —

    maximum time step specifies the largest time step size the DAE solver can use to evaluate the state. The maximum time step must be larger than minimum time step. The default is 1.

  • cdbl.png initial time step —

    initial time step specifies the time step size for the first time step that the DAE solver can use. The initial time step must be in range of the minimum time step and maximum time step. The default is 0.01.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • i1ddbl.png Times —

    Times returns the times at which the differential algebraic equation (DAE) solver evaluates the state.

  • i2ddbl.png X Values —

    X Values returns the values of the initial state over time. For X Values and X Derivatives, each row contains the values evaluated at a particular time and each column contains a history of a particular value over time.

  • i2ddbl.png X Derivatives —

    X Derivatives returns the values of the derivatives of the state over time. For X Values and X Derivatives, each row contains the values evaluated at a particular time and each column contains a history of a particular value over time.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Mathematics\Differential Equations - ODE\DAE Simple Pendulum Simulation.vi
    • labview\examples\Mathematics\Differential Equations - ODE\DAE Spring Pendulum Simulation.vi