Documentation of 'edu.jas.poly.TermOrder' Java class
TermOrder
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edu.jas.poly

Class TermOrder

  • All Implemented Interfaces:
    java.io.Serializable

    public final class TermOrder
extends java.lang.Object
implements java.io.Serializable
    Term order class for ordered polynomials. Implements the most used term orders: graded, lexicographical, weight aray and block orders. For the definitions see for example the articles Kredel, "Admissible term orderings used in computer algebra systems" and Sit, "Some comments on term-ordering in Gröbner basis computations". Note: the naming is not quite easy to understand: in case of doubt use the term orders with "I" in the name, like IGRLEX (the default) or INVLEX. Not all algorithms may work with all term orders, so watch your step. This class does not jet implement orders by linear forms over Q[t]. Objects of this class are immutable.
    See Also:
    Serialized Form

    • Constructor Detail

      • TermOrder

        public TermOrder()
        Constructor for default term order.

      • TermOrder

        public TermOrder(int evord)
        Constructor for given term order.
        Parameters:
        evord - requested term order indicator / enumerator.

      • TermOrder

        public TermOrder(long[] w)
        Constructor for given exponent weights.
        Parameters:
        w - weight vector of longs.

      • TermOrder

        public TermOrder(long[][] w)
        Constructor for given exponent weights.
        Parameters:
        w - weight array of longs.

      • TermOrder

        public TermOrder(int r,
                 int split)
        Constructor for default split order.
        Parameters:
        r - max number of exponents to compare.
        split - index.

      • TermOrder

        public TermOrder(int ev1,
                 int ev2,
                 int r,
                 int split)
        Constructor for given split order.
        Parameters:
        ev1 - requested term order indicator for first block.
        ev2 - requested term order indicator for second block.
        r - max number of exponents to compare.
        split - index.

    • Method Detail

      • getEvord

        public int getEvord()
        Get the first defined order indicator.
        Returns:
        evord.

      • getEvord2

        public int getEvord2()
        Get the second defined order indicator.
        Returns:
        evord2.

      • getSplit

        public int getSplit()
        Get the split index.
        Returns:
        split.

      • getWeight

        public long[][] getWeight()
        Get the weight array.
        Returns:
        weight.

      • getDescendComparator

        public TermOrder.EVComparator getDescendComparator()
        Get the descending order comparator. Sorts the highest terms first.
        Returns:
        horder.

      • getAscendComparator

        public TermOrder.EVComparator getAscendComparator()
        Get the ascending order comparator. Sorts the lowest terms first.
        Returns:
        lorder.

      • getSugarComparator

        public TermOrder.EVComparator getSugarComparator()
        Get the sugar order comparator. Sorts the graded lowest terms first.
        Returns:
        sugar.

      • equals

        public boolean equals(java.lang.Object B)
        Comparison with any other object.
        Overrides:
        equals in class java.lang.Object
        See Also:
        Object.equals(java.lang.Object)

      • hashCode

        public int hashCode()
        Hash code.
        Overrides:
        hashCode in class java.lang.Object
        See Also:
        Object.hashCode()

      • weightToString

        public java.lang.String weightToString()
        String representation of weight vector.
        See Also:
        Object.toString()

      • toString

        public java.lang.String toString()
        String representation of TermOrder.
        Overrides:
        toString in class java.lang.Object
        See Also:
        Object.toString()

      • extend

        public TermOrder extend(int r,
                        int k)
        Extend variables. Used e.g. in module embedding. Extend TermOrder by k elements. Note: todo distinguish TOP and POT orders.
        Parameters:
        r - current number of variables.
        k - number of variables to extend.
        Returns:
        extended TermOrder.

      • extendLower

        public TermOrder extendLower(int r,
                             int k)
        Extend lower variables. Extend TermOrder by k elements. Note: todo distinguish TOP and POT orders.
        Parameters:
        r - current number of variables.
        k - number of variables to extend.
        Returns:
        extended TermOrder.

      • contract

        public TermOrder contract(int k,
                          int len)
        Contract variables. Used e.g. in module embedding. Contract TermOrder to non split status.
        Parameters:
        k - position of first element to be copied.
        len - new length.
        Returns:
        contracted TermOrder.

      • reverse

        public TermOrder reverse()
        Reverse variables. Used e.g. in opposite rings.
        Returns:
        TermOrder for reversed variables.

      • reverse

        public TermOrder reverse(boolean partial)
        Reverse variables. Used e.g. in opposite rings.
        Parameters:
        partial - true for partialy reversed term orders.
        Returns:
        TermOrder for reversed variables.

      • revert

        public static int revert(int evord)
        Revert exponent order. Used e.g. in opposite rings.
        Parameters:
        evord - exponent order to be reverted.
        Returns:
        reverted exponent order.
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