text: All the three aerodynamic coefficients are integrals of the pressure coefficient curve along the chord.
  The coefficient of lift for a two-dimensional airfoil section with strictly horizontal surfaces can be calculated from the coefficient of pressure distribution by integration, or calculating the area between the lines on the distribution. This expression is not suitable for direct numeric integration using the panel method of lift approximation, as it does not take into account the direction of pressure-induced lift. This equation is true only for zero angle of attack.
  where:
  : is pressure coefficient on the lower surface
  : is pressure coefficient on the upper surface
  : is the leading edge location
  : is the trailing edge location
  When the lower surface  is higher (more negative) on the distribution it counts as a negative area as this will be producing down force rather than lift.