MnStrategy
org.freehep.math.minuit

Class MnStrategy



  • public class MnStrategyextends Object
    API class for defining three levels of strategies: low (0), medium (1), high (>=2).

    At many places in the analysis of the FCN (the user provided function), MINUIT must decide whether to be safe and waste a few function calls in order to know where it is, or to be fast and attempt to get the requested results with the fewest possible calls at a certain risk of not obtaining the precision desired by the user. In order to allow the user to infuence these decisions, the MnStrategy class allows the user to control different settings. MnStrategy can be instantiated with three different minimization quality levels for low (0), medium (1) and high (2) quality. Default settings for iteration cycles and tolerances are initialized then.

    The default setting is set for medium quality. Value 0 (low) indicates to MINUIT that it should economize function calls; it is intended for cases where there are many variable parameters and/or the function takes a long time to calculate and/or the user is not interested in very precise values for parameter errors. On the other hand, value 2 (high) indicates that MINUIT is allowed to waste function calls in order to be sure that all values are precise; it is it is intended for cases where the function is evaluated in a relatively short time and/or where the parameter errors must be calculated reliably.

    In addition all constants set in MnStrategy can be changed individually by the user, e.g. the number of iteration cycles in the numerical gradient.

    Acts on: Migrad (behavioural), Minos (lowers strategy by 1 for Minos-own minimization), Hesse (iterations), Numerical2PDerivative (iterations)

    • Constructor Detail

      • MnStrategy

        public MnStrategy()
        Creates a MnStrategy object with the default strategy (medium)
      • MnStrategy

        public MnStrategy(int stra)
        Creates a MnStrategy object with the user specified strategy.
        Parameters:
        stra - The use defined strategy, 0=low, 1 medium, 2=high.
    • Method Detail

      • strategy

        public int strategy()
      • gradientNCycles

        public int gradientNCycles()
      • gradientStepTolerance

        public double gradientStepTolerance()
      • gradientTolerance

        public double gradientTolerance()
      • hessianNCycles

        public int hessianNCycles()
      • hessianStepTolerance

        public double hessianStepTolerance()
      • hessianG2Tolerance

        public double hessianG2Tolerance()
      • hessianGradientNCycles

        public int hessianGradientNCycles()
      • isLow

        public boolean isLow()
      • isMedium

        public boolean isMedium()
      • isHigh

        public boolean isHigh()
      • setLowStrategy

        public void setLowStrategy()
      • setMediumStrategy

        public void setMediumStrategy()
      • setGradientNCycles

        public void setGradientNCycles(int n)
      • setGradientStepTolerance

        public void setGradientStepTolerance(double stp)
      • setGradientTolerance

        public void setGradientTolerance(double toler)
      • setHessianNCycles

        public void setHessianNCycles(int n)
      • setHessianStepTolerance

        public void setHessianStepTolerance(double stp)
      • setHessianG2Tolerance

        public void setHessianG2Tolerance(double toler)
      • setHessianGradientNCycles

        public void setHessianGradientNCycles(int n)

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