      context.setLineDash([]);
        context.closePath();
    }
}


///////
/// linear multiplier
function inc(counter_name) {
    var counter = document.getElementById(counter_name);
    counter.value = Number(counter.value) + 1;
    eval('change_' + counter_name + '()');
}

function dec(counter_name) {
    var counter = document.getElementById(counter_name);
    counter.value = Number(counter.value) - 1;
    eval('change_' + counter_name + '()');
}

function change_linear_multiplier() {
    var multipli