Increase result by 10% in loop

videoman

Hello, I am trying to create a loop that increase the radius of a circle by a certain percent (10%) every cycle (5 times in total). The radius is entered by the user.

I am trying to get the area of a circle to increase, by increasing the radius by 10% every cycle of a loop. I have started the script and have not managed to do it. The script below only increases the radius by 1 every loop.

<html>
<title>test</title>
</head>
<body>
<h1>test</h1>
<?php
$times = 5;
$i = 0;
$x = 0;
print '<hr />';
function getnum() {
$strThisPage = $SERVER['PHP_SELF'];
print '<form name="form1" method="post" action='.$strThisPage.'>';
print 'Number 1: <input type="text" name="number1" value=""><p />';
print '<p><input type="submit" /></p>';
print '</form>';
return;
}
if ($SERVER['REQUEST_METHOD'] != 'POST') {
getnum();
print '<hr />';
}
else {
$intNumber1 = $_POST['number1'];
$radius = $intNumber1;
$area = pi() * pow($radius, 2);
}
{
while ($x <= 5) {
$area++;
$x++;
print "Area of the circle is $area";
}
}
?>
</body>
</html>

Can someone please explain to me how to increase the radius (and thus the area by 10%) every loop?

P.S. I am also getting an error - "Notice: Undefined variable: area". Could someone please explain why I am getting that error? Thanks. Any help would be great.

Weedpacket

Well, you're not trying to increase the radius by 10%, you're increasing the area by 1 square pixel.
Increase $radius by 10%:

$radius = $radius+($radius/10);

And increasing the radius by 10% doesn't increase the area by 10%, it increases the area by 21%.

videoman wrote:
P.S. I am also getting an error - "Notice: Undefined variable: area". Could someone please explain why I am getting that error? Thanks. Any help would be great.

Because you're trying to use the value of a variable ($area) that hasn't been given a value.

videoman

Thankyou very much Weedpacket. I now understand how to increase a circles radius by 10%. Can you please help me with doing that in a loop? At the moment I can only increase the increment by 1 (using ++). How would I use the formula you gave me to increase the increment by 10% in the loop?

At the moment I am using "x" to make the loop go around 5 times. Is that a bad idea? Thanks

bpat1434

in your loop:

while($x <=5) // can also be done with for($x=1; $x<=5; $x++)
{
  if($x!=1)
    $radius = $radius+($radius/10);
  $area = pi() * pow($radius, 2);
  $x++; // Not necessary if you use the for() loop
  print 'Area of the circle is '.$radius.'<br>';
}

Weedpacket

videoman wrote:
How would I use the formula you gave me to increase the increment by 10% in the loop?

Like I said, you'd do that instead of increasing the area by 1. That's the line that says $area++ in case you were wondering.

videoman

Thanks so much Weedpacket and bpat1434. I have got it working ok now. earlier I tried putting the formula in the place of the $area++ but I forgot the "if" statement and it didn't work.

My current script looks like this-

<?php
$x = 0;
$area = 0;
$radius = 0;
$intNumber1 = 0;
print '<hr />';
function getnum() {
$strThisPage = $SERVER['PHP_SELF'];
print '<form name="form1" method="post" action='.$strThisPage.'>';
print 'Number 1: <input type="text" name="number1" value=""><p />';
print '<p><input type="submit" /></p>';
print '</form>';
return;
}
if ($SERVER['REQUEST_METHOD'] != 'POST') {
getnum();
print '<hr />';
}
else {
$intNumber1 = $_POST['number1'];
$radius = $intNumber1;
$area = pi() pow($radius, 2);
while($x <=5)
{
if($x!=1)
$radius = $radius+($radius/10);
$area = pi() pow($radius, 2);
$x++;
print 'radius of your original circle is '.$intNumber1.'<br>';
print 'radius of the circle plus 10% is '.$radius.'<br>';
print 'Area of the circle is '.$area.'<br> <br>';
}
}
?>
</body>
</html>

The only thing is that it prints the first block of text twice. Is there any way for me to stop that happening? Not that important but it will make my script even better if I can fix that small error. Thanks again