question: protected double LLToWorldReturningLon ( double lat , double lon , Point2D lp ) { double phi_deg = lat ; double phi = ProjMath . degToRad ( phi_deg ) ; double lamba_deg = lon ; double lamba = ProjMath . degToRad ( lamba_deg ) ; double dlamda = lamba - lamdaf ; if ( dlamda > Math . PI ) { dlamda -= MoreMath . TWO_PI_D ; } else if ( dlamda < - Math . PI ) { dlamda += MoreMath . TWO_PI_D ; } double e = ellps . ecc ; double r = 0.0d ; if ( ! MoreMath . approximately_equal ( Math . abs ( phi ) , MoreMath . HALF_PI , EPS10 ) ) { double t = lambTsfn ( phi , Math . sin ( phi ) , e ) ; r = ellps . radius * F * Math . pow ( t , n ) ; } double theta = n * dlamda ; double easting = falseEasting + r * Math . sin ( theta - alpha ) ; double northing = falseNorthing + rf - r * Math . cos ( theta - alpha ) ; lp . setLocation ( easting , northing ) ; return dlamda ; }
target:  LLToWorld that returns normalized longitude in radians, to be used for more calculations in some methods. Do not provide a NULL lp here if you want the world coordinates provided back to you.