lib/RungeKutta4.js
function(derives, xStart, yStart, h) {
    this.derives    = derives
    this.x          = xStart
    this.y          = yStart || []
    this.dimension  = this.y.length
    this.h          = h || 0.01

    // cache the k1, k2, k3, k4 of each step
    this._k1
    this._k2
    this._k3
    this._k4
}
function(derives, xStart, yStart, h) {
    this.derives    = derives
    this.x          = xStart
    this.y          = yStart || []
    this.dimension  = this.y.length
    this.h          = h || 0.01

    // cache the k1, k2, k3, k4 of each step
    this._k1
    this._k2
    this._k3
    this._k4
}
function ( derives , xStart , yStart , h ) { this . derives = derives this . x = xStart this . y = yStart || [ ] this . dimension = this . y . length this . h = h || 0.01 // cache the k1, k2, k3, k4 of each step this . _k1 this . _k2 this . _k3 this . _k4 }
The fourth order Runge-Kutta integration method

@class RungeKutta4
@param {Function} derives Differential equations which needed to integrate
@param {Number}   xStart  Initial value problem: x0
@param {Array}    yStart  Initial value problem: y0
@param {Number}   h       Each step-size value
The fourth order Runge - Kutta integration method