matlab输出的2进制数之间用空格隔开

[hxy110]

A = xlsread('Tt3.xlsx');
C = arrayfun(@(x)dec2binPN(x,17),A,'UniformOutput',false);
M = cell2mat(C);
a = strvcat(M);
[x,y] = size(a);
fid = fopen('Tt.txt','wb');
for i = 1:x
fprintf(fid,'%s\n',a(i,:));
end
fclose(fid);
程序如上，想让a的每一行都是没17个字符后显示一空格，怎么加循环，让如下加循环
A = xlsread('Tt3.xlsx');
C = arrayfun(@(x)dec2binPN(x,17),A,'UniformOutput',false);
M = cell2mat(C);
a = strvcat(M);
[x,y] = size(a);
fid = fopen('Tt.txt','wb');
for i = 1:x
for j =1:17:136
fprintf(fid,'%s\n',a(i,:));
fprintf(fid,'%s ',a(i,j:j+17));
end
end
fclose(fid);
结果只是a的从第二行起前17个字符之后有空格