Description:
------------
var_dump() does not show the actual value of floats; but rather performs rounding before rendering.

This can lead to hard to decipher loss of precision bugs. If you then use var_dump() to try to compare output, you aren't going to find the *actual* values of the numbers you are comparing.

For this reason, I'd like to ask var_dump() renders the complete representation of the number; where needed in scientific notation.
 

Reproduce code:
---------------
<?php
function variance($a, $b) {
    return (double)100.00 -  (double)(($a/$b) * 100.00);
}

var_dump(12.99);                   //12.99
var_dump(variance(87.01, 100.00)); //12.99

var_dump(variance(87.01, 100.00) - 12.99); //difference      <-5.3290705182008E-15>


Expected result:
----------------
---------- php ----------
float(12.99)
float(12.99) // should be 12.99 + -5.3290705182008E-15
float(-5.3290705182008E-15)

Output completed (0 sec consumed) - Normal Termination

Actual result:
--------------
---------- php ----------
float(12.99)
float(12.99)
float(-5.3290705182008E-15)

Output completed (0 sec consumed) - Normal Termination