# FPGA设计代做-Mie效率的计算

### 时间：2018-12-5 3:14:02 点击：

核心提示：Mie效率的计算...
function result = Mie(m, x)

% Computation of Mie Efficiencies for given
% complex refractive-index ratio m=m'+im"
% and size parameter x=k0*a, where k0= wave number in ambient
% medium, a=sphere radius, using complex Mie Coefficients
% an and bn for n=1 to nmax,
% s. Bohren and Huffman (1983) BEWI:TDD122, p. 103,119-122,477.
% Result: m', m", x, efficiencies for extinction (qext),
% scattering (qsca), absorption (qabs), backscattering (qb),
% asymmetry parameter (asy=) and (qratio=qb/qsca).
% Uses the function "Mie_abcd" for an and bn, for n=1 to nmax.
% C. M妕zler, May 2002.

if x==0 % To avoid a singularity at x=0
result=[real(m) imag(m) 0 0 0 0 0 0 1.5];
elseif x>0 % This is the normal situation
nmax=round(2+x+4*x^(1/3));
n1=nmax-1;
n=(1:nmax);cn=2*n+1; c1n=n.*(n+2)./(n+1); c2n=cn./n./(n+1);
x2=x*x;
f=mie_abcd(m,x);
anp=(real(f(1,:))); anpp=(imag(f(1,:)));
bnp=(real(f(2,:))); bnpp=(imag(f(2,:)));
g1(1:4,nmax)=[0; 0; 0; 0]; % displaced numbers used for
g1(1,1:n1)=anp(2:nmax); % asymmetry parameter, p. 120
g1(2,1:n1)=anpp(2:nmax);
g1(3,1:n1)=bnp(2:nmax);
g1(4,1:n1)=bnpp(2:nmax);
dn=cn.*(anp+bnp);
q=sum(dn);
qext=2*q/x2;
en=cn.*(anp.*anp+anpp.*anpp+bnp.*bnp+bnpp.*bnpp);
q=sum(en);
qsca=2*q/x2;
qabs=qext-qsca;
fn=(f(1,:)-f(2,:)).*cn;
gn=(-1).^n;
f(3,:)=fn.*gn;
q=sum(f(3,:));
qb=q*q'/x2;
asy1=c1n.*(anp.*g1(1,:)+anpp.*g1(2,:)+bnp.*g1(3,:)+bnpp.*g1(4,:));
asy2=c2n.*(anp.*bnp+anpp.*bnpp);
asy=4/x2*sum(asy1+asy2)/qsca;
qratio=qb/qsca;
result=[real(m) imag(m) x qext qsca qabs qb asy qratio];
end;

Tags:MIE效率

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