Home > atmlab > mie > mie_S12nopeak.m

mie_S12nopeak

PURPOSE ^

Computation of Mie Scattering functions S1 and S2

SYNOPSIS ^

function result = mie_S12nopeak(m, x, u)

DESCRIPTION ^

 Computation of Mie Scattering functions S1 and S2
 without the diffraction pattern to avoid the forward peak
 of the scattering phase function.
 Complex refractive index m=m'+im", 
 size parameter x=k0*a, and u=cos(scattering angle),
 where k0=vacuum wave number, a=sphere radius;
 s. p. 110-114, Bohren and Huffman (1983) BEWI:TDD122
 C. M�zler, March 2004

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

DOWNLOAD ^

mie_S12nopeak.m

SOURCE CODE ^

0001 function result = mie_S12nopeak(m, x, u)
0002 
0003 % Computation of Mie Scattering functions S1 and S2
0004 % without the diffraction pattern to avoid the forward peak
0005 % of the scattering phase function.
0006 % Complex refractive index m=m'+im",
0007 % size parameter x=k0*a, and u=cos(scattering angle),
0008 % where k0=vacuum wave number, a=sphere radius;
0009 % s. p. 110-114, Bohren and Huffman (1983) BEWI:TDD122
0010 % C. M�zler, March 2004
0011 
0012 nmax=round(2+x+4*x^(1/3));
0013 ab=mie_ab(m,x);
0014 an=ab(1,:);
0015 bn=ab(2,:);
0016 
0017 pt=mie_pt(u,nmax);
0018 pin =pt(1,:);
0019 tin =pt(2,:);
0020 
0021 n=(1:nmax);
0022 n2=(2*n+1)./(n.*(n+1));
0023 pin=n2.*pin;
0024 tin=n2.*tin;
0025 S1=(an*pin'+bn*tin');
0026 S2=(an*tin'+bn*pin');
0027 xs=x.*sqrt(1-u.*u);
0028 % Computation of diffraction pattern S according to BH, p. 110
0029 if abs(xs)<0.0001
0030     S=x.*x*0.25.*(1+u);            % avoiding division by zero
0031 else
0032     S=x.*x*0.5.*(1+u).*besselj(1,xs)./xs;    
0033 end;
0034 % Subtracting the diffraction pattern to avoid the forward peak
0035 % of the scattering phase function.
0036 result=[S1-S;S2-S];

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