Java floor floory(double a, double precision)

Description

Returns the largest (closest to positive infinity) double value that is not greater than the argument and is equal for at least a precision value.

License

Open Source License

Return

⌊a/precision⌋*precision = Math.floor(a/precision)*precision.

Declaration

public static double floory(double a, double precision)

Method Source Code

//package com.java2s;

public class Main {
    /**//from ww  w.  j  av  a 2  s. c o  m
     * The default tolerance for two numbers to be treated equal.
     * (experimental)
     * @see #setDefaultTolerance(double)
     * @invariants DefaultTolerance &ge; 0
     */
    private static double DefaultTolerance = .00000000001;

    /**
     * Returns the largest (closest to positive infinity)
     * <code>double</code> value that is not greater than the argument and
     * is equal for at least a precision value.
     * <code>MathUtilities.floory(a, .01)</code> will result in <code>a</code> rounded down
     * to a number formated as <code>.##</code>,
     * while <code>MathUtilities.floory(a, 100)</code> will result in <code>a</code> rounded down
     * to a number formated as <code><i>several #s preceding</i>######<b>00</b>.</code>.
     * @return &lfloor;a/precision&rfloor;*precision = <code>Math.floor(a/precision)*precision</code>.
     * @see #ceily(double, double)
     */
    public static double floory(double a, double precision) {
        return Math.floor(a / precision) * precision;
    }

    public static double floory(double a) {
        return floory(a, precisionFor(a));
    }

    /**
     * Get the precision for a given a specified tolerance relative to the magnitude of a.
     * <p>
     * Roughly gives the precision for tolerance percent of a, but adjusted to decimal digits.
     * </p>
     * @return tolerance * 10<sup>&lceil;&#13266;<sub>10</sub> a&rceil;</sup>.
     */
    public static double precisionFor(double a, double tolerance) {
        return tolerance * Math.pow(10, Math.ceil(Math.log(a) / Math.log(10)));
    }

    /**
     * Get the precision for a default tolerance relative to the magnitude of a.
     */
    public static double precisionFor(double a) {
        return precisionFor(a, DefaultTolerance);
    }
}