In Matlab 2016a, Mathworks deprecated the use of the sym function for parsing symbolic expressions:
>> expr = sym('x + 1')
Warning: Support of strings that are not valid variable names or define a number will be
removed in a future release. To create symbolic expressions, first create symbolic
variables and then use operations on them.
> In sym>convertExpression (line 1536)
In sym>convertChar (line 1441)
In sym>tomupad (line 1198)
In sym (line 177)
expr =
x + 1
The warning's suggestion is not practical when the symbolic expressions are being read from a file rather than built by hand in code. Is there a function in Matlab to replace this functionality? I would rather not regexprep and eval my way through it.
In Matlab 2017b, the str2sym function was added to replace the lost functionality of parsing a string into a symbolic expression. It works essentially like sym used to:
>> expr = str2sym('x + 1')
expr =
x + 1