src/Common.php
public static function pj_enfn($es)
    {
        $en = array();
        $en[0] = static::C00 - $es * (static::C02 + $es * (static::C04 + $es * (static::C06 + $es * static::C08)));
        $en[1] = $es * (static::C22 - $es * (static::C04 + $es * (static::C06 + $es * static::C08)));
        $t = $es * $es;
        $en[2] = $t * (static::C44 - $es * (static::C46 + $es * static::C48));
        $t *= $es;
        $en[3] = $t * (static::C66 - $es * static::C68);
        $en[4] = $t * $es * static::C88;

        return $en;
    }
public static function pj_enfn($es)
    {
        $en = array();
        $en[0] = static::C00 - $es * (static::C02 + $es * (static::C04 + $es * (static::C06 + $es * static::C08)));
        $en[1] = $es * (static::C22 - $es * (static::C04 + $es * (static::C06 + $es * static::C08)));
        $t = $es * $es;
        $en[2] = $t * (static::C44 - $es * (static::C46 + $es * static::C48));
        $t *= $es;
        $en[3] = $t * (static::C66 - $es * static::C68);
        $en[4] = $t * $es * static::C88;

        return $en;
    }
public static function pj_enfn ( $ es ) { $ en = array ( ) ; $ en [ 0 ] = static :: C00 - $ es * ( static :: C02 + $ es * ( static :: C04 + $ es * ( static :: C06 + $ es * static :: C08 ) ) ) ; $ en [ 1 ] = $ es * ( static :: C22 - $ es * ( static :: C04 + $ es * ( static :: C06 + $ es * static :: C08 ) ) ) ; $ t = $ es * $ es ; $ en [ 2 ] = $ t * ( static :: C44 - $ es * ( static :: C46 + $ es * static :: C48 ) ) ; $ t *= $ es ; $ en [ 3 ] = $ t * ( static :: C66 - $ es * static :: C68 ) ; $ en [ 4 ] = $ t * $ es * static :: C88 ; return $ en ; }
code from the PROJ.4 pj_mlfn.c file;  this may be useful for other projections

@param float $es
@return float
code from the PROJ . 4 pj_mlfn . c file ; this may be useful for other projections