Confusion about calculation of aerodynamic moments

[Nikhil05]

Hello,

Can anybody explain how the aerodynamic moment is calculated for an airfoil ?
I was reading the first chapter in "Fundamentals of Aerodynamics" by Anderson & the formula for aerodynamic moment for the lower surface of the airfoil confused me. Is the aerodynamic moment calculated about some other point for the lower surface ?
Thank you.

 

[AeroTron]

need more information like page where to find in that book?

 

[Nikhil05]

no need now, i figured it out myself. was just interpreting it wrongly.