Module org.scijava.ops.image

Package org.scijava.ops.image.filter.fftSize

Class NextSmoothNumber

java.lang.Object

org.scijava.ops.image.filter.fftSize.NextSmoothNumber

public final class NextSmoothNumber
extends Object

A class to determine the next k-smooth number (i.e. a number divisible only by prime numbers up to k), given a lower bound n. Based on A. Granville, Smooth numbers: computational number theory and beyond:

5.7. Finding smooth numbers computationally. The obvious way to find y-smooth numbers in (x; x + z) with z ≤ x is to initialize an array a[i] := 0 for 1 ≤ i ≤ z (where a[i] corresponds to x + i). For each successively larger prime power p^j ≤ x + z with p ≤ y, determine the smallest i such that p^j divides x + i and then add log(p) to a[i], a[i + p^j], a[i + 2p^j] and so on, up until the end of the array. When we’ve finished, if any a[i] ≥ log(x), then x + i is y-smooth.

Author:

Johannes Schindelin, Brian Northan

Method Summary

Modifier and Type	Method	Description
static int	nextSmooth(int x)
static int	nextSmooth(int y, int x, int z)

Methods inherited from class java.lang.Object

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

Method Detail

nextSmooth

public static int nextSmooth(int x)

nextSmooth

public static int nextSmooth(int y,
                             int x,
                             int z)