Determines a zero of a 1D function in a given interval. The function has to be continuous and has to have different signs at the end points of the interval. You must manually select the polymorphic instance to use.


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Inputs/Outputs

  • cdbl.png accuracy —

    accuracy controls the accuracy of the zero determination. The default is 1.00E-8.

  • cdbl.png start —

    start is the leftmost point of the interval. The default is 0.0.

  • cdbl.png end —

    end is the rightmost point of the interval. The default is 0.0.

  • cstr.png formula —

    formula is a string describing the function. The formula can contain any number of valid variables.

  • idbl.png zero —

    zero is the determined zero of formula. zero is a good approximation only for the exact value.

  • idbl.png f(zero) —

    f(zero) is the function value at the point given by zero. The answer should be very close to zero.

  • iu32.png ticks —

    ticks is the time effort for the whole calculation of the function values in milliseconds.

  • ii32.png error —

    error returns any error or warning from the VI. When start > end, the application interprets it as an error condition. The function values at the points start and end must have different signs to guarantee the existence of a zero in (start,end). You can wire error to the Error Cluster From Error Code VI to convert the error code or warning into an error cluster.

    • Given the function f(x) with f(a)*f(b) < 0, Ridders' method determines c = (a + b)/2 and calculates the new guess using the following equation:

    The values start, cnew, and end are the base for the new iteration, depending on which of the following inequalities is true:

    f(start) · f(cnew) < 0 f(cnew) · f(end) < 0

    The algorithm stops if |a – b| < accuracy.

    Ridders' method is very fast and reliable.

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Mathematics\Scripts and Formulas\Street Illumination Problem.vi