MATLAB 二进制转换四进制时出错的问题

ytm

请大佬看看这段程序

function [y,yn]=two2four(x,m)
7 L/ L5 g! m% r4 b0 x%二进制转换成四进制
syms x
T=[0 1;3 2];
n=length(x);
ii=1;
for i=1:2:n-1;
    xi=x(i:i+1)+1;
+ `4 f# c* P, u: O3 v$ q% ?1 l    yn(ii)=T(xi(1),xi(2));
    ii=ii+1;
end
yn=yn-1.5;
y=yn;
for i=1:m-1;
" L4 s3 m! I1 D! [% K2 C/ c    y=[y;yn];
end
y=y(';
. H" m2 w$ E, I' w7 v& A运行显示
??? Undefined function or variable "yn".
Error in ==> two2four at 12
! C4 }! [7 r0 _0 xyn=yn-1.5;
* i0 S# t! t& Z3 D, _
, W" R6 z2 F9 {. X# t

fawa

yn=yn-1.5;这句代码有错，左侧的yn=右侧的yn-1.5
1 g  P. ?* x1 {9 P& \6 e但右侧的yn在前面的代码中未定义，所以报错，定义一下就好