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):
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);
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?
The 2nd code is an m-file with name derivative.
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')
This is the huge code which i thought.Maybe when you see that you have headache.
But my really problem is how to calculate the integral and about that i need your help if anyone knows.
Thank You!!
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February 24th, 2009, 11:38 AM
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