how to change the direction of the airfoil

I want to change direction of the airfoil in the opposite way,what function do i need or what line do i need to fix? Here is my code.

Answer 1

[Alan Stevens]

Change

contourf(real(J),imag(J),imag(f),v2); %%%%%
fill(real(zair),imag(zair),'k')

to

contourf(-real(J),imag(J),imag(f),v2); %%%%%
fill(-real(zair),imag(zair),'k')