How to Call a Javascript Function Placed in wp_footer hook?

I have a javascript function that I want to call from a button I've placed in a form on a Wordpress Page.

I put the Javascript code in the wp_footer hook as suggested in a few other posts here (hopefully this was the right place.)

The button is in a Wordpress Page and I've called the function using:

<input type="button" onclick="calcrent()" value="Calculate" class="button">

Nothing happens when I click the button, so I'm guessing I need to change something about the way the function called? Or do I need to place something inside the Javascript itself?

Thanks.