MATLAB: Why the save instruction not execute correctly in matlab 2013 , code is below

Question

x=100;
>> save('test.mat','x');
Error using save
Unable to write file test.mat: permission denied.
>> x=100;
>> save('test.mat','x','append');
Error using save
Variable 'append' not found.

Answer 1

Try '-append' instead of 'append'.