Performs numerical integration using adaptive quadrature approach. You must manually select the polymorphic instance to use.


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Inputs/Outputs

  • cfxdt.png data —

    data is a variant that you can use to pass arbitrary values to the integrand VI.

  • csvrn.png integrand —

    integrand is a strictly typed reference to the VI that implements the expression to integrate. Create this VI by starting from the VI template located in labview\vi.lib\Analysis\8numeric.llb\1D Quadrature Integrand.vit.

    Note The elements in the X array and Y array of the integrand VI specify the values of the two integral variables at different time stamps. The X array and Y array represent the first and second variables, respectively, so you cannot separate the elements in the X array and Y array.
  • cdbl.png upper limit —

    upper limit is the upper limit of the integral. The default is 1.

  • cdbl.png lower limit —

    lower limit is the lower limit of the integral. The default is 0.

  • cdbl.png tolerance —

    tolerance controls the accuracy of the quadrature. A smaller tolerance leads to a more accurate result but more computation time. The default is 1E-5.

  • idbl.png result —

    result returns the integral result.

  • ii32.png error —

    error returns any error or warning from the VI. You can wire error to the Error Cluster From Error Code VI to convert the error code or warning into an error cluster.

    • This VI compares the difference between the 4-points and 7-points Lobatto quadratures on the interval with tolerance to terminate the calculation iteration. If the difference is less than the tolerance, the algorithm stops the iteration and moves on to next interval.

    1D Quadrature

    This VI numerically evaluates the following integral using the adaptive Lobatto quadrature:

    where x1 is the upper limit and x0 is the lower limit.

    To obtain high accuracy, this VI divides an interval into subintervals when the integrand f(x) varies sharply, as shown in the following front panel.

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Mathematics\Integration and Differentiation\VI Reference Based Quadrature.vi