Package org.apache.commons.math.optimization.general

Enum ConjugateGradientFormula

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<ConjugateGradientFormula>
    public enum ConjugateGradientFormula
extends java.lang.Enum<ConjugateGradientFormula>
    Available choices of update formulas for the β parameter in NonLinearConjugateGradientOptimizer.

    The β parameter is used to compute the successive conjugate search directions. For non-linear conjugate gradients, there are two formulas to compute β:

    • Fletcher-Reeves formula
    • Polak-Ribière formula
    On the one hand, the Fletcher-Reeves formula is guaranteed to converge if the start point is close enough of the optimum whether the Polak-Ribière formula may not converge in rare cases. On the other hand, the Polak-Ribière formula is often faster when it does converge. Polak-Ribière is often used.

    Since:
    2.0
    See Also:
    NonLinearConjugateGradientOptimizer

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description
      FLETCHER_REEVES
      Fletcher-Reeves formula.
      POLAK_RIBIERE
      Polak-Ribière formula.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static ConjugateGradientFormula valueOf​(java.lang.String name)
      Returns the enum constant of this type with the specified name.
      static ConjugateGradientFormula[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.

      • Methods inherited from class java.lang.Enum

        compareTo, equals, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

    • Method Detail

      • values

        public static ConjugateGradientFormula[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (ConjugateGradientFormula c : ConjugateGradientFormula.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static ConjugateGradientFormula valueOf​(java.lang.String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        java.lang.IllegalArgumentException - if this enum type has no constant with the specified name
        java.lang.NullPointerException - if the argument is null