Pityke Ormester

package main

/**
 * Created by endre on 5/28/17.
 *
 * It intends to prototype a method to solve non-linear equations in an iterative way.
 * f(x) = e^x - 2
 * find x for f(x) = 0
 * f'(x) = e^x
 *
 * deltaX = x_current - x_prev
 * xNext = xCurrent + deltaX
 * f(x) = f(x_current) + f'(x_current) * deltaX  (f(x) = 0)
 */


fun main(args: Array<String>) {
    fun f(x: Float):Float = Math.pow(Math.E, x.toDouble()).toFloat() - 2f
    fun df(x: Float):Float = Math.pow(Math.E, x.toDouble()).toFloat()

    var xCurrent = 0f
    for(i in 0..4) {
        println("--- Iteration: $i ---")
        println("x$i = ${xCurrent}")
        val f_xCurrent = f(xCurrent)
        println("f(x$i) = ${f_xCurrent}")
        val df_xCurrent = df(xCurrent)
        println("f'(x$i) = ${df_xCurrent}")
        val deltaX = -(f_xCurrent / df_xCurrent)
        println("deltaX = -f(x$i)/f'(x$i) = ${deltaX}")
        xCurrent += deltaX
    }
}