edu.stanford.math.plex

Class PlexSort.Comp

java.lang.Object

edu.stanford.math.plex.PlexSort.Comp

Enclosing class:

PlexSort

public abstract static class PlexSort.Comp
extends java.lang.Object

Instances of the Comp inner class are used as comparison closures for the sorting routine comp_sort. In addition to the obvious uses, such as sorting in decreasing order, using closures allows us to sort arrays of points by increasing or decreasing density (or any other real-valued function on the points). There are also some slightly non-obvious applications, which we probably won't use here, such a computing the inverse of a permutation stored in an array p[]. If p is [1,2,0] -- that is, the permutation mapping 0->1, 1->2, 2->0, then let x = [0,1,2], and sort the entries of x[i] so that x[i] is less than x[j] iff p[x[i]] < p[x[j]]. Then the sorted contents of x are [2,0,1]. This is the inverse of p[].

Constructor Summary

Constructors

Constructor and Description
PlexSort.Comp()

Method Summary

Methods

Modifier and Type	Method and Description
abstract int	fn(int i, int j) Compare two int arguments, and return an integer less than, equal to, or greater than 0, depending on whether i is respectively less, equivalent, or greater than, j.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PlexSort.Comp

public PlexSort.Comp()

Method Detail

fn

public abstract int fn(int i,
     int j)

Compare two int arguments, and return an integer less than, equal to, or greater than 0, depending on whether i is respectively less, equivalent, or greater than, j.

Parameters:

i - The first argument.

j - The second argument.

Returns:

an int that is -/0/+ -- intuitively, return (i-j) for an increasing sort.