Numerical Integration of Combined Functions with Conditional

I want to integrate the following function from 0 to Y for various values of Pm and Pt:

T(y) = 1/(1/Pm + N/Pt)

where N = n^2*U*y*[ 1 - exp (-n^2*U*y ) ] and U(y)=y for y<11.05 otherwise U(y)=ln(y)/K + C.

Constants are K=0.42, C=5.5, n=0.125.

I've tried to compose a combined function T(N,y) but "integral" keeps giving me errors. Anyone have any idea if this can be done.

Answer 1

[Andrei Bobrov]

Y = 20;
[p1,p2]=ndgrid(1:3,6:8);
integral(@(x)T(x,p1,p2),0,Y,'ArrayValued',1)

here T-function as m-file: T.m

function out = T(y,Pm,Pt)
    K=0.42;
    C=5.5;
    n=0.125;
    if y < 11.05
        u = y;
    else
        u = log(y)/K + C;
    end
    N = n^2*u.*y.*(1 - exp (-n^2*u.*y ));
    out = 1./(1./Pm + N./Pt);
end

[Walter Roberson]

I recommend adding 11.05 as a 'waypoints' in the integral() call.