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[yj112358]

matlab编程求复数函数，然后对复数函数求模，得到的结果里面却有复数i？不知怎么回事，
代码如下：
syms n2 k0 fa1 fa2 k2 real ;
syms c v0 fw alpha real;
syms sild kmax d kxmax kx delta sild real;
syms v real ;
syms Rsf Rs RA1 real;
nord=1.46;next=1.57;n1=1;c=3*(10^8);alpha=pi/2;fa1=pi/3;n2=1.383;k2=0.0083;v0=2923.443;sild=0;kmax=0.6;d=2.17*10^(-9);fw=20.77174;k0=2*pi*v/1000;
nx=next*(sin(sild))^2+nord*(cos(sild))^2;
f=0.5*(3*(cos(sild))^2-1);
kxmax=kmax*(f*(sin(alpha))^2/2+(1-f)/3);
V=2*pi*c*fw;
delta=2*pi*c*(v-v0);
kx=kxmax*V^2/(4*delta^2+V^2);
Nx=nx+kx*i;
N2=n2+k2*i;
I1=d*(Nx^2-N2^2);
I2=k0/N2*sin(fa1)*I1;
I3=I2*i;
fa2=asin(n1/N2*sin(fa1));
b=-sin(fa1-fa2)+I3;
b1=sin(fa1+fa2)-I3;
rs=b/b1;
rf=sin(fa1-fa2)/sin(fa2+fa1);
Rsf=rf*conj(rf);
Rs=rs*conj(rs);
%Rsf=real(rf)*real(rf)+imag(rf)*imag(rf);
%Rs=real(rs)*real(rs)+imag(rs)*imag(rs);
RA1=-log10(Rs/Rsf)