# root-mean-square

5 replies to this topic

### #1 brown2005

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Posted 27 July 2006 - 12:21 PM

hi,

does anyone know how to write php code for a root mean square, i was brosing on the net and saw it and wanted to know how it was done.

### #2 Kris

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Posted 27 July 2006 - 12:25 PM

hi,

does anyone know how to write php code for a root mean square, i was brosing on the net and saw it and wanted to know how it was done.

I don't fully understand, do you want to know how to calculate the RMS of an array of values?

### #3 brown2005

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Posted 27 July 2006 - 12:28 PM

well i saw on a rating thing, they use a root mean square to combat someone who just keeps putting 1111111111111111111111111111111 for everone...

so i wanted to know how they do it

### #4 Kris

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Posted 27 July 2006 - 12:50 PM

I don't understand how this will help, RMS "is a statistical measure of the magnitude of a varying quantity". I'm not brilliant in maths, but I think this is how you work out the RMS of an array of values:
```<?php
function rms() {
\$vals = func_get_args();
\$new = "";
foreach(\$vals as \$n) \$new += pow(\$n,2);
\$new = sqrt(\$new / count(\$vals));
echo \$new;
}
?>```
Someone that is good at maths, please do go ahead and correct me if I'm wrong.

### #5 brown2005

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Posted 27 July 2006 - 01:18 PM

ok.. ill try.. so in a rating system wat would you use, just a normal average?

### #6 Kris

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Posted 27 July 2006 - 02:04 PM

ok.. ill try.. so in a rating system wat would you use, just a normal average?

Personally, yes. Maybe you could filter out all ratings that are full of 1's...

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