Defines the right side of a partial differential equation and its coefficients. You must manually select the polymorphic instance to use.


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Inputs/Outputs

  • cNI__PDE_lvlib_NI__PDElvclass.png PDE in —

    PDE in is the class that stores the data of the equation.

  • c2ddbl.png F(t, x) —

    F(t, x) specifies the value of right side of the equation.

    The size of the right side of the equation must be # of t-points-by-# of x-points from the Define PDE Domain VI. Each row or column of F(t, x) stores the value of the right side of the equation evaluated on point X from the Define PDE Domain VI at a particular time step. By default, LabVIEW assumes the values of F(t, x) are zeros.

  • cdbl.png k —

    k is a squared value that specifies the coefficient of the second order partial derivative of the unknown function in the equation. k cannot be 0. The default is 1.

  • cdbl.png a —

    a specifies the coefficient of the unknown function in the equation. The default is 0.

  • cerrcodeclst.png error in (no error) —

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

  • iNI__PDE_lvlib_NI__PDElvclass.png PDE out —

    PDE out returns the right side of PDE in and its coefficients.

  • ierrcodeclst.png error out —

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

    • Helmholtz Equation

    The following equation defines the Helmholtz equation:

    where k and a are constant coefficients, u is the unknown function, and f is the right side of the equation. The operator is the Laplacian. The Laplacian in Cartesian coordinates is defined as

    in two-dimensional space and

    in three-dimensional space.

    Heat Equation

    The following equation defines the general form of the heat equation:

    Wave Equation

    The following equation defines the general form of the wave equation:

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Mathematics\Differential Equations - PDE\PDE Flexible Element.vi
    • labview\examples\Mathematics\Differential Equations - PDE\PDE String Vibration.vi
    • labview\examples\Mathematics\Differential Equations - PDE\PDE Thermal Distribution.vi