公式转换成matlab代码

将公式xi+1=a(sin(yi)+b)xi(1-xi)
yi+1=a(sin(xi+1)+b)yi(1-yi)转换成matlab代码，分岔图上一片空白，请问是哪里出了问题

{a=1;
b=3;

x0=1;
y0=0.1;

N1 = 500; %前面迭代个数
N2 = 8000; % 后面迭代个数

w0 = zeros(N1+N2,2);

for i = 1: N1+N2
x= a*(sin(y0 * pi/180)+b)x0(1 - x0);
y=a*(sin(x* pi/180)+b)y0(1- y0);

x0 = x;
y0 = y;
w0(i,1) = x;
w0(i,2) = y;
end}