Exponentiation in a Formula

[grahamhow424]

Hi

I am trying to figure out how to duplicate a, financial, calculation
that uses the caret, Exponentiation.

Here's the formula...

A = 0.0755
B = 34
C = 50000
D = 22448

result = ((C-D)*A/12)/(1-(1+A/12)^(-B))+D*A/12

It calculates loan repayments based on interest rate (A), number of
payments (B), total loan amount (C) and a residual amount (D).

This calculation will work when the caret (Exponentiation) is used,
however this is not available in Javascript. So, to get this formula to
work in Javascript some other method needs to be used.

I have found examples of how to do Exponentiation, like this:

/***********************************************************/

function powmod(base,exp,modulus)
{
var accum=1, i=0, basepow2=base;
while ((exp>>i)>0)
{
if(((exp>>i) & 1) == 1){accum = (accum*basepow2) % modulus;};
basepow2 = (basepow2*basepow2) % modulus;
i++;
};
return accum;
}

/***********************************************************/

This function comes from here
http://www.math.umbc.edu/~campbell/N...pt.html#PowMod (some handy stuff
there) but I can't replicate the calculation I have posted using a
function like that.

Anyone know how to do this?

Thanks!

 

[-Lost]

Hi

I am trying to figure out how to duplicate a, financial, calculation
that uses the caret, Exponentiation.

Here's the formula...

A = 0.0755
B = 34
C = 50000
D = 22448

result = ((C-D)*A/12)/(1-(1+A/12)^(-B))+D*A/12

result = ((C-D)*A/12)/(1-Math.pow((1+A/12),(-B)))+D*A/12;

-Lost

 

[grahamhow424]

Hi David

Thanks, I got it now.

The formula I posted previously could translate in JS as...

var A1 = 0.0755;
var B1 = 34;
var C1 = 50000;
var D1 = 22448;

alert(((C1 - D1) * A1 / 12) / (1 - Math.pow((1 + A1 / 12), -B1)) + (D1
* A1 / 12));

Thanks again!

 

[-Lost]

Hi David

Thanks, I got it now.

The formula I posted previously could translate in JS as...

var A1 = 0.0755;
var B1 = 34;
var C1 = 50000;
var D1 = 22448;

alert(((C1 - D1) * A1 / 12) / (1 - Math.pow((1 + A1 / 12), -B1)) + (D1
* A1 / 12));

result = ((C-D)*A/12)/(1-Math.pow((1+A/12),(-B)))+D*A/12;

That is the exact same thing I wrote (a few minutes before you posted again).

-Lost

 

[grahamhow424]

Ahhhh -Lost

You nailed it. Unfortunately I sorted it out while you were posting,
wish you posted about 3 mins earlier!

Anyway, thanks a lot, appreciate your input.

 

[Dr J R Stockton]

In comp.lang.javascript message

I am trying to figure out how to duplicate a, financial, calculation
that uses the caret, Exponentiation.

In Javascript, X = Base^Expo is actually bitwise exclusive-or, and
X = Math.pow(Base, Expo) exponentiates. Read any relevant book.

It's a good idea to read the newsgroup and its FAQ. See below.

 

[-Lost]

Ahhhh -Lost

You nailed it. Unfortunately I sorted it out while you were posting,
wish you posted about 3 mins earlier!

Anyway, thanks a lot, appreciate your input.

Heh. No problem!

-Lost