Problem with Woocommerce code working

Can you tell me why my code is not working?

add_action( 'woocommerce_single_product_summary', 'woocommerce_total_product_price', 31 );
function woocommerce_total_product_price() {
    global $woocommerce, $product; 
    // let's setup our divs 
    echo sprintf('<div id="product_total_price" style="margin-bottom:20px;">%s %s</div>',__('Prezzo Totale:','woocommerce'),'<span class="price">'.$product->get_price().'</span>');
    ?>
    <script>
        jQuery(function($){
            var price = <?php echo $product->get_price(); ?>,
                currency = '<?php echo get_woocommerce_currency_symbol(); ?>';

            $('[name=quantity]').change(function(){
                if (!(this.value < 1)) {

                    var product_total = parseFloat(price * this.value);

                    $('#product_total_price .price').html( currency + product_total.toFixed(2));

                }
            });
        });
    </script>
    <?php
}