Trying to integrate for drag

I am trying to inegrate using an array with 56 numbers. The formula is rho*integral of uwake(20- uwake) where uwake is the array.

for i=1:totalpts
    data=load(fullfile(dir_address,[ifname '_' num2str(i) '.mat']));
    dP(i)=mean(data.dp) * (249.0);   % differntial pressure % This data is in (inches of water) convert it into SI units 
    Pressure_Atm(i)=data.pAtm;     % atomspheric pressure 
    Temp_Atm(i)=data.tAtm;     % atomsheric temperature at each measured point 
    z(i)=data.zCurr * (0.0254);        % position of the each  point along the Z axis of the windtunnel % This data is in inches convert it into SI units 
    u_wake = sqrt((2*dP)/rho);
end
plot(u_wake,z);
Integrate = u_wake(20-u_wake);
Drag = rho*trapz(Integrate)

Answer 1

[Walter Roberson]

I suspect

Integrate = u_wake .* (20-u_wake);