function innerProduct( x ) {
	/* eslint-disable no-invalid-this */
	var ret = 0;
	var i;
	for ( i = 0; i < x.length; i++ ) {
		ret += this._data[ i ] * x[ i ];
	}
	ret += ( this.intercept ) ? this._data[ i ] : 0.0;
	ret *= this.scale;
	return ret;
}
Calculates the inner product of the weights and supplied vector `x`.

@private
@param {NumericArray} x - input vector
@returns {number} inner product