/**
* Estimates the approximate index for a given number
* It uses the approximate formula:
* F(n) ~ (PHI^n)/sqrt(5), where '~' means the 'closest integer to'
* This equation is based on the relation: phi = -1/PHI
* Which turns Lucas' formula into:
* F(n) = (PHI^2n + 1)/(PHI^n * sqrt(5))
* From which we get the formula above, after making the approximation:
* (PHI^2n + 1) -> (PHI^2n)
*
* @param integer $num
* @return integer the approximate index
* @access private
*/
function &_estimateN(&$num)
{
/*{{{*/
if (Math_IntegerOp::isMath_Integer($num)) {
$f = $num->toString();
} else {
$f = $num;
}
return Math_Fibonacci::_closestInt((log($f) + MATH_LNSQRT5) / MATH_LNPHI);
}
/**
* Checks that the passed object is a valid Math_Integer number.
* The object must be an instance of Math_Integer and have been properly
* initialized.
*
* @param object Math_Integer $int1
* @return mixed TRUE if is a Math_Integer object, PEAR_Error otherwise
* @access private
*/
function _validInt(&$int1)
{
/*{{{*/
$error = '';
if (!Math_IntegerOp::isMath_Integer($int1)) {
$error = 'Is not a Math_Integer object.';
} elseif (!$int1->initialized()) {
$error = 'Math_Integer object is uninitalized.';
}
if (!empty($error)) {
return PEAR::raiseError($error);
} else {
return true;
}
}