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Find a Minimum nD (Downhill Simplex » VI) (G Dataflow)

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    Last Modified: January 12, 2018

    Uses the downhill simplex method to determine a local minimum of a function of n independent variables defined with a strictly typed VI reference.

    The downhill simplex method relies only on function evaluations and is able to find a solution when the function is not smooth and does not have derivatives defined.

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    data

    Arbitrary values passed to the strictly typed VI reference.

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    objective function

    Strictly typed reference to the VI that implements the objective function.

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    start

    Values of the variables at which the optimization starts.

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    error in

    Error conditions that occur before this node runs.

    The node responds to this input according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

    Default: No error

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    stopping criteria

    Conditions that terminate the optimization.

    This node terminates the optimization if this node reaches all the tolerance thresholds or passes any of the maximum thresholds.

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    function tolerance

    Minimum relative change in function values between two internal iterations.

    Definition of Relative Change in Function Values

    The relative change in function values between two internal iterations is defined as follows:

    abs ( f n f n 1 ) abs ( f n ) + ε

    where

    • fn is the function value of the current iteration
    • fn - 1 is the function value of the previous iteration
    • ε is the machine epsilon

    Default: 1E-06

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    parameter tolerance

    Minimum relative change in parameter values between two internal iterations.

    Definition of Relative Change in Parameter Values

    The relative change in parameter values between two internal iterations is defined as follows:

    abs ( P n P n 1 ) abs ( P n ) + ε

    where

    • Pn is the parameter value of the current iteration
    • Pn - 1 is the parameter value of the previous iteration
    • ε is the machine epsilon

    Default: 1E-06

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    gradient tolerance

    Minimum 2-norm of the gradient.

    Default: 1E-06

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    maximum iterations

    Maximum number of iterations that the node runs in the optimization.

    Default: 100

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    maximum function calls

    Maximum number of calls to the objective function allowed in the optimization.

    Default: 1000

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    maximum time

    Maximum amount of time in seconds allowed for the optimization.

    Default: -1 — The optimization never times out.

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    minimum

    Values of the variables where the objective function has the local minimum.

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    f(minimum)

    Value of the objective function at minimum.

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    function calls

    Number of times that this node called the objective function(s) in the optimization.

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    error out

    Error information.

    The node produces this output according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

    Where This Node Can Run:

    Desktop OS: Windows

    FPGA: Not supported

    Web Server: Not supported in VIs that run in a web application


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