Performs a discrete differentiation on x.

This VI is similar to the Derivative x(t) VI.

Note By default, reentrant execution is enabled in all Point By Point VIs.


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Inputs/Outputs

  • cbool.png initialize —

    initialize, when TRUE, initializes the internal state of the VI.

  • cdbl.png x —

    x is an input data point.

  • cdbl.png initial condition —

    initial condition is the value used to calculate the derivative for the first and second point. The default is 0.

  • cdbl.png dt —

    dt is the sampling interval and must be greater than zero. The default is 1.0.

    If dt is less than or equal to zero, the VI returns an error.

  • idbl.png dx/dt —

    dx/dt is the differentiated data point.

  • 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 uses the 2nd Order Central method to calculate the differentiation. Let y represent the output dx/dt. y is given by the following equations:

    y0 = (x0 – initial condition)/2dt y1 = (x1 – initial condition)/2dt yj = (xj+1 – xj–1) / 2dt, for j = 2, 3, 4, …

    where yj is the output dx/dt of the (j+1)th call of this VI and xj is the input x of the (j+1)th call of this VI.