关于matlab的程序问题，为什么会出现‘Subscript indices must either be real positive integers or logi

程序如下：
clc;
clear all;
k1=20; k2=1;
q=0.1;    %噪声强度
Ap=0.3;    %信号幅值
f=0.1/(2*pi);    %信号频率
L=0.1;
p=i*2*pi*f;
h=k1*L/q;  
b=k1^2/(2*p*q);   
r1=sqrt(1+4*p*q/k1^2); 
r2=sqrt(1+4*p*q/k2^2);
v=k2/k1;    %delt
lang=1-exp(h);  %朗姆达
u=1-exp(h*r1);
a1=sqrt(1-u)-1/(sqrt(1-lang));
a2=sqrt(1-u)-sqrt(1-lang);
S=q/(2*p*b*v^2)*(2+2*h*v+h^2*v^2-(h^2+2*h+2*lang))*v^3/(1-lang*v);   %方差
m=0;             %均值

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%上面一段是各个参数的赋值
A0=4*q*b*lang*u*(1-4*v)/(1-lang*v);
A1=-8*q*b*(1-v)*((1-lang)*a1^2+a2^2)*r1;
A2=2*q*(2*lang*u*(2-v)-4*v*u+v*lang*(2-u)*r1)/(1-lang*v);
A3=-4*q*r1*((2-v)*a2^2+v*lang(2+(2-u)*r2))/(v^2*(1-lang*v)*(1+r2));
A4=-4*q*r1*a1^2*(2-3*v)*(1-lang)/(v^2*(1-lang*v)*(1+r2));
A5=2*q*u*((2-v)*lang+2*v(2-lang)*r2+2*v(1-lang))/(v^2*(1-lang*v)*(1+r2));
A6=q*r1*(2-u)*(v*lang*(1+r2)-6+2*v-2*r2)/(b*v^2*(1-lang*v)*(1+r2));
A7=2*q*u(1+v*(2-lang)-2*v^2*lang)*r2/(b*v^2*(1-lang*v)*(1+r2));
A8=2*q*u(3+4*lang-2*v^2*lang-v(2+3*lang))/(b*v^2*(1-lang*v)*(1+r2));
A9=4*q*u/(b^2*v^3*(1+r2));
B=p^2*(1+r2)^2*((2-u)*r2-u(1-v+v*r2));
A=[A0,A1,A2,A3,A4,A5,A6,A7,A8,A9];
K=S^2/p+sum(A)/B;
SNR_out=Ap^2*(S+m-p*K)^2/(q*pi*real(K))
%%点击程序运行到A3那里出现‘Subscript indices must either be real positive integers or logicals’，A3如果用笔算也能算出，为什么matlab会出现这样的问题，之后的A5,A7,A8,A9都是同样的问题，求高手帮助！！！！！