Why are some extended ASCII characters not retained after closing and reopening an M file in releases prior to MATLAB R2022a?

I am using MATLAB R2014b. When I create an M file that contains the line "a = 'δ'" and execute it, it runs normally.  However, when I close the M file and reopen it, the line reads "a = '?'" in the code editor.  Running the script assigns the question mark character to the variable "a".  

Why doesn't MATLAB preserve alternate characters like delta in the editor?

Answer 1

[MathWorks Support Team]

As of MATLAB R2022a, MATLAB fully supports UTF-8 encoding and can support characters such as delta as desired. For more information, please see the MATLAB R2022a Release Notes. Changes to fully support Unicode characters can be seen starting in R2020a, with the support completed with the release of R2022a.

Since you are using MATLAB R2014b, the described behavior is expected because the UTF-8 delta character is not properly saved. To resolve this issue, you can upgrade to a more recent version of MATLAB such as MATLAB R2022a or newer. 

[Walter Roberson]

The exact version for UTF-8 support depends on which operating system you are using, and on whether you are using the English interface or one of the Asian language interfaces. If I recall correctly, limited support started before R2020a.