Help in performing Numerical integration

Background: This equation models light distribution in a bioreactor. It's a function of radius of bioreactor(r), Cell number(C) & Incident light on the reactor (I_s).

For now, I would assume that C & I_s remains constant, where C = 1.17*10^6 and I_s = 82 and the integration would have a limit of r = 0.042 to r =0.05

I = 2.*pi.*r.*I_s.*(exp(-0.079.*(50-r))+6*10^(-9)*C^(-2.5))/(exp(3.5*10^(-10).*C.*(50-r))+6*10^(-9)*C^(-2.5))

Anyone can help me out with a coding that performs a trapezoidal integration on this equation?

Answer 1

[Andrei Bobrov]

>> C = 1.17*10^6;
I_s = 82;
r = linspace(0.042,0.05,100);
I = 2.*pi.*r.*I_s.*(exp(-0.079.*(50-r))+6*10^(-9)*C^(-2.5))./(exp(3.5*10^(-10).*C.*(50-r))+6*10^(-9)*C^(-2.5));
out = trapz(I,r)
out =
     0.003603