Q:

JavaScript clear text box input not functioning properly

I know that this is an embarassingly easy question, but I can't figure out the problem, and that's why I'm asking the question, so please don't reiterate this point. 
Anyway, I'm just working on something here, and when I tested my page to see how things were going, I realized that my calculate() method isn't clearing text input like I want it to. 
Here is the markup and the script:
<! DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Quadratic Root Finder</title>
<script>
function calculate(){
var valuea = document.form1.variablea.value;
var valueb = document.form1.variableb.value;
var valuec = document.form1.variablec.value;
document.form1.variablea.value = "";
document.form1.variableb.value = "";
document.form1.variablec.value = "";
}
</script>
</head>

<body>
<form name="form1">
    a:<input name="variablea" value="" type="text">
    <br/>
    b:<input name="variableb" value="" type="text">
    <br/>
    c:<input name="variablec" value="" type="text">
    <br/>
    <input name="calculate" value="Calculate!"  type="button" onClick="calculate()">
</form>
</body>
</html>

Please tell me if you see anything. 

A:

You might want to try using another name.  I tried to call the "calculate" function but it keeps on giving me an error saying "calculate" is not a function.  But when I call the function "calculateQuad" and change the onClick event to call "calculateQuad" it works.