try:
http://www.zend.com/manual/function.eval.php
Cal
http://www.calevans.com
-----Original Message-----
From: Paul Cohen [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, January 17, 2001 6:14 PM
To: [EMAIL PROTECTED]
Subject: [PHP] String to Variable converstion
Hello all,
I am trying to build an IRR calculator using PHP. The number of cash flow
streams I will have at any time will vary, so I am using a loop to build the
formula. Then I am iterating to solve the equation and output the solution.
As most of you know, I am solving the following for r:
0=SUM SERIES(CF(i)/{(1+r)^n))
I can build my formula sucessfully with the following;
$form="";
while ($row=mysql_fetch_array($result)){
$form.="$CF/pow((1+'$r'),$N)";
}
But it recognizes $form as a string, so when I put it in my "solution for r"
loop:
for($r=-1.00; $r<=1.00; $r=$r+.0001){
if($form>-.001 && $form < .001){
$IRR=round($r*100, 2);
}
}
echo "$IRR%<br>";
BTW, I have also tried building the $form as a variable, but since I don't
have a value for $r it just puts in zero and sets $form equal to the right
side of the equation. Therfore, instead of inserting a formula into my
"solution for r" loop, it inserts a constant for $form.
I think my solution is to build the formula as a string and then insert it
into my "solution for r" loop, convert it back to a real formula and then
iterate for the solution. Is this possible? If not, any suggestions?
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