I posted earlier today looking for some help making a calculator for the school project Im working on, the problem is that I need to use the Newton-Raphson method on the APR calculator Im trying to make. Below is a link to my site (the original is hosted on Blackboard) that has the formulas on it. Any help or pointers would be awesome, this thing is just being a huge pain, I got the first part of the equation down, heres the link:
and heres my code:
function stripComma(val) {
	return val.replace(/[,\s]/gi,'');

function apr() { 
		var loan = stripComma($('loanamount').value);
		loan = Number(loan);
		var rate = stripComma($('intrestrate').value);
		rate = Number(rate);
		var months = stripComma($('monthnum').value);
		months = Number(months);
		var extra = stripComma($('extra').value);
		extra = Number(extra);

		if(loan == '' || extra == '' || rate == '' || months == '' ) 
        	alert ('Please be sure to fill in ALL of the required fields!');
		//this does the first steps in calculating the APR by finding the monthly payments as per the directions
		rate = rate /1200;
		newrate = rate + 1;
		newrate = Math.pow(newrate, months);
		extra = extra + loan;
		extra = extra * rate;
		extra = extra * newrate;
		bottomnum = newrate - 1;
		payments = exta / bottomnum;
Thx again all