[問題]●MATLAB嫩咖求助~參數定義問題
這是我在國外論壇找到的一個半導體模擬，
但一開始該程式作者提到aj和eta定義，到底function要怎打?
以下是程式:
function xx=fermi(aj,eta)
% Matlab m file to evaluate the Half-order Fermi-Dirac integral
% For semiconductor/solid state applications
% Half-order implies that j (= aj)= -1/2 or 1/2 or 3/2 or 5/2
% Created on 5-Jan-2007 by Natarajan and Mohankumar
%========================================================
% Based on the Published work below
% Title: The accurate numerical evaluation of half-order
% Fermi-Dirac integrals
% Authors: N.Mohankumar & A.Natarajan
% Journal: Physica Status Solidi(b) vol.188, 1995, pp. 635-644
%============================================================
% xx is a dummy output
% eta and aj are input values to be given by the user.
% Printed output is the integral value.
% Input variable aj is same as j in the definition of F(j,eta) given below
% Accuracy: For solid state physics applications, eta values
% typically lie in the interval [-5,25]; For eta in [-5,25],
% the code below is guaranteed to yield 14 digit accuracy.
%============================================================
% Integral definition is given below
%
% Integral is defined by F(j,eta)
% Integrand is defined by (x^j)/[Gamma(1+j)* (exp(x-eta)+1)]
% Lower limit=0; Upper limit=infinity
% Integrated with respect to x
% Please check whether your definition of the integral
% needs the Gamma(1+j) factor or not.
%===================================================================
% Trapezoidal Integration in y after the transformation
% from the original integration variable x to y
% where x= y^2
% Residue correction for the poles of the transformed integrand is
% added to the trapezoidal integration sum to expedite convergence
%=========================================================
%Program begins
format long e;
%==============================================================
% Evaluation of Trapezoidal sum begins
range=8.;
if eta > 0.
range=sqrt(eta+64.);end;
h=0.5;
nmax=range/h;
sum=0.;
if aj== (-0.5)
sum=1./(1.+exp(-eta));end;
for i=1:nmax
u=i*h;
ff=2.*(u^(2.*aj+1))/(1.+exp(u*u-eta));
sum=sum+ff;end;
%Trapezoidal Summation ends
%==============================================================
% Pole correction for trapezoidal sum begins
pol=0.;
npole=0;
% Fix the starting value of BK1 to start while loop
bk1=0;
while bk1 <= 14.*pi
npole=npole+1;
bk=(2*npole -1)*pi;
rho=sqrt(eta*eta+bk*bk);
t1=1;
t2=0;
if eta < 0;
tk=- aj*(atan(-bk/eta)+pi);
elseif eta ==0;
tk=0.5*pi*aj;
else;
eta > 0;
tk=aj*atan(bk/eta);
end;
rk=- (rho^aj);
tk=tk+0.5*atan(t2/t1);
if eta < 0
rk= -rk;
end;
ak=(2.*pi/h)*sqrt(0.5*(rho+eta));
bk1=(2.*pi/h)*sqrt(0.5*(rho-eta));
if bk1 <= (14.*pi)
gama=exp(bk1);
t1=gama*sin(ak+tk)-sin(tk);
t2=1.-2.*gama*cos(ak)+gama*gama;
pol=pol+4.*pi*rk*t1/t2;
end; %ends if loop above
end; % Top while loop ends
npole=npole-1;
fdp=sum*h+pol;
% Program ends with the following output
%===============================================================================
disp('Fermi-Dirac Integral Value');
disp(fdp/gamma(1+aj));
disp('Number of trapezoidal points & number of poles');
disp([round(nmax),npole]);
--
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