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Excel spreadsheet formula to javascript question

Answer 1

A:

I believe the problem is with the ^. In javascript, ^ does not mean exponent like it does in VB. You have to use the Math.pow method instead. Try this JavaScript:

var theCalc = (0.49 * 99500) / Math.pow( 1 - (1 + 0.49), -48 );

David 2010-07-06 19:57:57

Looking at his original code, I would think the divisor should be (1 - Math.pow((1+.49), -48)

Tommy 2010-07-06 19:59:00

David: i get 6.567967606278839e-11 when doing that...

StealthRT 2010-07-06 20:02:18

Tommy: i get 48755.00023718012 when using your code...

StealthRT 2010-07-06 20:03:50

added a comment to your question and an answer below. I think it was a combination of what David mentioned, using Math.pow, having your divisor in the correct order and using .0049 instead of .49

Tommy 2010-07-06 20:06:35

Answer 2

A:

<html>
<head>
<title>test</title>
</head>

<body onload="testfun();">

<script type="text/javascript"> 
function testfun(){
    document.getElementById('testRes').innerHTML = (.0049 * 99500) / (1 - Math.pow((1+.0049), -48));
}
</script>

The answer:
<div id="testRes"></div>

This gives a result of 2331.290084493742

Tommy 2010-07-06 20:05:48

Changing the .49 to 0.0049 did the trick with your code, Tommy but how do i round it since the answer is 2331.290084493742 and it should be 2,332?

StealthRT 2010-07-06 20:08:07

I think we are seeing a little floating point math / rounding error between Excel and JS. For example, changing my code to this: ((.0049 * 99500).toFixed(4) / (1 - Math.pow((1+.0049), -48)).toFixed(4)).toFixed(0), gives a result of 2,332. Basically, using the toFixed properties to limit the number of decimals coming out of each part of the function, then using .toFixed(0) to return the whole number. I think you're on the right track, just need to see how much precision you need in these numbers.

Tommy 2010-07-06 20:14:30

Ah, thanks Tommy. That did it :o)

StealthRT 2010-07-06 20:22:46

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