As the English definition implies, "append" means there's got to be something already there to append to. While computer-language definitions don't always have a direct correlation to the equivalent word in common usage, it appears that is the case with save.
>> dir x.*
'x.*' not found.
>> save x -append
Error using save
Unable to write file x: No such file or directory.
>>
It errors if there isn't an existing .mat file on which to append the existing array.
>> save x
>> save x -append
>> delete x.mat
>> x=[];
>> save x
>> x=rand(10,1);
>> save x -append
>> clear x
>> load x
>> whos x
Name Size Bytes Class Attributes
x 10x1 80 double
>>
Closest I could come was to create an empty file first; you could do that as part of an initialization step and then the remaining code could, it appears, be identical even for the first "real" case.
