Question

I am trying to find whether a variable that I am calculating falls within a 20% range of a predefined number.

For example: predefined number is 8 (20% is 1.6) so the number would need to fall between 6.4 and 9.6.

What would be the best way to do this via PHP please?

//——————- APOLOGIES FOUND A WORKING ANSWER

Apologies worked this out by thinking about it!

Here is the code for others:

// Calculating the variables and defining the top and bottom ($read = 8 for example)
$calspeed = $read * 0.2;
$topspeed = $read + $calspeed;
$btmspeed = $read - $calspeed;

// $avg is taken from a sql query drawn from database
if ($avg > $btmspeed && $avg < $topspeed){
    echo "this is an acceptable reading speed";
}else{
    echo "wrong";
}

Answer 1

<?PHP
$predefined = <<WHATEVER>>;
$range = (float) $predefined * 0.2;
if ( $range > abs( (float)$input - (float)$predefined))) {
  //Declare Victory
}

This has the benefit of supporting integers and allows you to coerce the values into something similar for the more complicated data formats.