aureooms/js-polynomial

/**
 * Model for a little endian polynomial evaluation function.
 *
 * @param  {function} mov      number move function
 * @param  {function} imov     number in place move function
 * @param  {function} iadd     number in place addition function
 * @param  {function} mul      number multiplication function
 * @param  {function} imul     number in place multiplication function
 * @return {function} polynomial evaluation function
 */

export function __evaluate__ ( mov , imov , iadd , mul , imul ) {

    /**
     * Evaluates little endian polynomial [i , j[ for x.
     *
     * @param  {const polynomial}  p the polynomial to evaluate
     * @param  {index} i             left index of polynomial
     * @param  {index} j             right index of polynomial
     * @param  {const number} x      number for which the polynomial is evaluated
     * @param  {number} y            0 initialized number
     * @return {number}              param y
     */

    var evaluate = function ( p , i , j , x , y ) {

        var X ;

        if ( i < j ) {

            y = imov( y , p[i] ) ;

            ++i ;

            if ( i < j ) {

                // X = x^k , for k in [0 , j - i[

                X = mov( x ) ;

                y = iadd( y , mul( X , p[i] ) ) ;

                for ( ++i ; i < j ; ++i ) {

                    X = imul( X , x ) ;

                    y = iadd( y , mul( X , p[i] ) ) ;

                }

            }

        }

        return y ;

    } ;

    return evaluate ;

}