//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
/** @author  John Miller
 *  @version 1.1
 *  @date    Sat Feb  2 20:21:38 EST 2013
 *  @see     LICENSE (MIT style license file).
 */

package scalation.math

import math.{abs, log}                           // absolute value, natural log

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/** The `Basic` object provides additional methods for computing logarithms and a
 *  method for transforming Booleans into Ints.
 */
object Basic
{
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    /** Return 1 if the condition is true else 0.
     *  @param cond  the condition to evaluate
     */
    def oneIf (cond: Boolean): Int = if (cond) 1 else 0

    /** The natural log of 2
     */
    val log_of_2  = log (2.0)

    /** The natural log of 10
     */
    val log_of_10 = log (10.0)

    //::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
    /** Compute the log of x base 2
     *  @param x  the value whose log is sought
     */
    def log2 (x: Double): Double = log (x) / log_of_2

    //::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
    /** Compute the log of x base 2
     *  @param x  the value whose log is sought
     */
    def log10 (x: Double): Double = log (x) / log_of_10

    //::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
    /** Compute the log of x base b
     *  @param b  the base of the logarithm
     *  @param x  the value whose log is sought
     */
    def logb (b: Double, x: Double): Double = log (x) / log (b)

    //::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
    /** Return the absolute value of 'x' with the sign of 'y'.
     *  @param x  the value contributor
     *  @param y  the sign contributor
     */
    def sign (x: Double, y: Double): Double =
    {
        if (y < 0.0) -abs (x) else abs (x)
    } // sign

} // Basic object


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/** The `BasicTest` object is used to test the `Basic` object.
 */
object BasicTest extends App
{
    import Basic._

    println ("oneIf (2 > 1) = " + oneIf (2 > 1))
    println ("log2 (2)      = " + log2 (2.0))
    println ("log2 (4)      = " + log2 (4.0))
    println ("log10 (10)    = " + log10 (10.0))
    println ("log10 (100)   = " + log10 (100.0))
    println ("logb (4, 4)   = " + logb (4.0, 4.0))
    println ("logb (4, 16)  = " + logb (4.0, 16.0))
    println ("sign (4, -2)  = " + sign (4, -2))

} // BasicTest object