Arithmetics Series

/**

 * Class to provide arithmatics services using Javascript

 * 

 * @author  : irfanudin ridho

 * @email   : irfan.ub@gmail.com

 * @date    : December 25, 2010

 * @version : 2.0 

 */

/**

 * Constructor service

 * @param start the first value of the series

 * @param diff the difference between the values in the series

 * @n how many value in the series

 */

function ArithmeticSeries(start,diff,n){
    this.data = new Array();
    this.start = start;
    this.diff = diff;
    this.n = n;
}

/**

 * method to get the series

 * @return array of the series

 */
ArithmeticSeries.prototype.getSeries = function(){
    for(i=0;i<this.n;i++){
        this.data[i] = this.start + (this.diff*i);
    }
    return this.data;
}

/**

 * method to get the total sum of the individual value of

 * the series.

 * @return sum total summation of the series.

 */
ArithmeticSeries.prototype.getSum = function(){
    var sum = 0;
    for(i=0;i<this.n;i++){
        sum = sum+(this.start+(this.diff*i));
    }
    return sum;
}

/**

 * method to get the last item of the series

 * @return the last item

 */
ArithmeticSeries.prototype.getLast = function(){
    return this.getSeries()[this.getSeries().length-1];
}

/**

 * method to get the first item in the series

 * @return the first item in the series

 */
ArithmeticSeries.prototype.getFirst = function(){
    return this.getSeries()[0];
}

/**

 * method to get the n-th item of the series 

 * @return the n-th item of the series

 */
ArithmeticSeries.prototype.getNth = function(n){
    var bound = this.getSeries().length;

    if(typeof n=='undefined')
        return 'please supply an argument';

    else if(n<=0)
        return 'index must be positive';
   
    else if(n>bound)
        return 'index out of bounds';

    else
        return this.getSeries()[n-1];
}