Convert energy from db scale to linear scale.

Description

Demo Code

/**// w w w  .j a  v a  2s  .  c o  m
 * Copyright 2004-2006 DFKI GmbH.
 * All Rights Reserved.  Use is subject to license terms.
 * 
 * Permission is hereby granted, free of charge, to use and distribute
 * this software and its documentation without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of this work, and to
 * permit persons to whom this work is furnished to do so, subject to
 * the following conditions:
 * 
 * 1. The code must retain the above copyright notice, this list of
 *    conditions and the following disclaimer.
 * 2. Any modifications must be clearly marked as such.
 * 3. Original authors' names are not deleted.
 * 4. The authors' names are not used to endorse or promote products
 *    derived from this software without specific prior written
 *    permission.
 *
 * DFKI GMBH AND THE CONTRIBUTORS TO THIS WORK DISCLAIM ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL DFKI GMBH NOR THE
 * CONTRIBUTORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
 * THIS SOFTWARE.
 */
//package com.java2s;

public class Main {
    /** The Constant LOG10. */
    protected static final double LOG10 = Math.log(10);

    /**
     * Convert energy from db scale to linear scale.
     *
     * @param dbEnergy the db energy
     * @return energy on a linear scale.
     */
    public static double db2linear(double dbEnergy) {
        if (Double.isNaN(dbEnergy))
            return 0.;
        else
            return exp10(dbEnergy / 10);
    }

    /**
     * Db2linear.
     *
     * @param dbEnergies the db energies
     * @return the double[]
     */
    public static double[] db2linear(double[] dbEnergies) {
        return exp10(divide(dbEnergies, 10));
    }

    /**
     * Exp10.
     *
     * @param x the x
     * @return the double
     */
    public static double exp10(double x) {
        return Math.exp(LOG10 * x);
    }

    /**
     * Exp10.
     *
     * @param a the a
     * @return the double[]
     */
    public static double[] exp10(double[] a) {
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = exp10(a[i]);
        }
        return c;
    }

    /**
     * Divide.
     *
     * @param a the a
     * @param b the b
     * @return the double[]
     */
    public static double[] divide(double[] a, double[] b) {
        if (a.length != b.length) {
            throw new IllegalArgumentException(
                    "Arrays must be equal length");
        }
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = a[i] / b[i];
        }
        return c;
    }

    /**
     * Divide.
     *
     * @param a the a
     * @param b the b
     * @return the double[]
     */
    public static double[] divide(double[] a, double b) {
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = a[i] / b;
        }
        return c;
    }

    /**
     * Divide.
     *
     * @param x the x
     * @param a the a
     * @return the double[][]
     */
    public static double[][] divide(double[][] x, double a) {
        return multiply(1.0 / a, x);
    }

    /**
     * Exp.
     *
     * @param a the a
     * @return the double[]
     */
    public static double[] exp(double[] a) {
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = Math.exp(a[i]);
        }
        return c;
    }

    /**
     * Multiply.
     *
     * @param a the a
     * @param b the b
     * @return the double[]
     */
    public static double[] multiply(double[] a, double[] b) {
        if (a.length != b.length) {
            throw new IllegalArgumentException(
                    "Arrays must be equal length");
        }
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = a[i] * b[i];
        }
        return c;
    }

    /**
     * Multiply.
     *
     * @param a the a
     * @param b the b
     * @return the double[]
     */
    public static double[] multiply(double[] a, double b) {
        double[] c = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            c[i] = a[i] * b;
        }
        return c;
    }

    /**
     * Multiply.
     *
     * @param a the a
     * @param x the x
     * @return the double[][]
     */
    public static double[][] multiply(double a, double[][] x) {
        double[][] z = null;

        if (x != null) {
            int i, j;
            for (i = 1; i < x.length; i++)
                assert x[i].length == x[0].length;

            z = new double[x.length][x[0].length];

            for (i = 0; i < x.length; i++) {
                for (j = 0; j < x[i].length; j++)
                    z[i][j] = a * x[i][j];
            }
        }

        return z;
    }
}
Convert energy from db scale to linear scale. - Java java.lang

Description

Demo Code

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