Looking for Stack/Method in RW to provide day of the week

I want to enter any date in three dropdown menus DD/MM/YYYY with the end result of knowing the associated day of the week. I have an app that does this. Is there a way to install apps into a rapidweaver page?

Here is a PHP snippet for you… throw this into an HTML stack and set your page to be php.

$date = new DateTime('2000-01-01');
echo "<p>".$date->format('l')."</p>";

Thanks for your reply but I fear I am too stupid to understand how it would work, especially with the gregorian and Julian calendars. My fault as I wasn’t clear enough in my explanation what I was looking for. So here is I hope a clearer explanation.
I would enter the date I want the day of the week for as DD/MM/YYYY. The range of dates would be from the 1500s to the present. Hence my reference to Julian and Gregorian calendars. So the year would be a drop down list starting from as early as 1565 say.

Formloom and formsnap date-pickers do this in Gregorian and go back to 1500’s. However, it is of course a form so not sure how you would work this with your needs.