Hi everyone,

i have a difficult exercise in matlab and i need your help if anyone knows.

The idea of this exercise is to insert a theoretical equation Cdot in Matlab.With the results which it'll give me,i want to create a theoretical graph with axis x(v) and y(Cdot).Finally this graph i want to compare it with one experimental graph which i have.Summary,my goal is to find the best combination of ndot,M,edot in which the theoretical graph to be quite similar to experimental graph(sorry for my bad English).

The equation which i have is:

a=1/(1+exp((E - Vdot)/(k*T)))

b=(G*Ndot)/sqrt((pi*M)/2)

c=exp(-2((E + Edot + Vdot)/M)^2)

Cdot=q*A*L∂/∂v∫a*b*c dE

where Vdot=v/L and M=de(this name i gave it in my code).The integral i want to be [0,+inf] with respect to E.

The total equation which i want to insert in matlab is Total=Cdot1+Cdot2+C.

Cdot1,Cdot2 are 2 different distrubutions and

C=A*(sqrt((q*ep*e0*Nd)./(2*(Vbi-v-k*T))))

Now the code which i thought is:

Firstly,i make 2 m-files with names integral1,integral2 which has this function(everything i do here is the same with m-file integral2):

My problem is the last 2 lines.I'm not sure if this is the best way to find the integral.Also,if i try quad (inline_final1,0,inf) then all the values are NaN.Why?Code:function subtotal1=integral1(ndot1,de1,v1) A=12.56e-4; %this value is static,not change L=0.44; %this value is static,not change G=2; %this value is static,not change T=300.0; %this value is static,not change q=1.6e-19; %this value is static,not change k=8.62e-5; %this value is static,not change(Boltzman) Edot1=-0.3; %between -0.6-0.6 syms E; %(define) E a=1/(1+exp((E-(v/L))/(k*T))); b=(G*ndot1)./(sqrt((pi*de1)/2)); ek8eths1=((E+Edot1+(v/L))/de1).^2; c=exp(-2*ek8eths1); final1=a.*c*b; inline_final1 = vectorize (inline (char (final1))); subtotal1 = quad (inline_final1,0,1e13);

The 2nd code is an m-file with name derivative.

This is the huge code which i thought.Maybe when you see that you have headache.Code:clear all clc A=12.56e-4; L=0.44; q=1.6e-19; ep=13; e0=8.85e-14; Nd=2e15; Vbi=2; k=8.62e-5; T=300.0; i=1; %1st distribution ndot1=3e10; de1=0.1; %2nd distribution ndot2=9e10; de2=0.1; v=-12:0.05:1.5; C=A*(sqrt((q*ep*e0*Nd)./(2*(Vbi-v-k*T)))); for i=1:1; for j=1:length(v) fintegrals1(j,i)=integral1(ndot1(i),de1(i),v(j)); fintegrals2(j,i)=integral2(ndot2(i),de2(i),v(j)); end end deriv1=-(diff(fintegrals1))./0.05; % (Q2-Q1)/(V2-V1) deriv2=-(diff( fintegrals2))./0.05; total1=deriv1.*(q*A*L); total2=deriv2.*(q*A*L); C=C.'; %1x280 to 280x1 totaly=C+total1+total2; path(path,'c:\thodoris') %here i have the experimental values load askisi2.txt plot(askisi2(:,1),askisi2(:,2),v,totaly) title('Ari8mitikh Epilisi') xlabel('V') ylabel('Col') legend('peiramatiki','8ewritiki')

But my really problem is how to calculate the integral and about that i need your help if anyone knows.

Thank You!!