MATLAB: Error using str2sym (line 213)

str2symsymbolic equationSymbolic Math Toolbox

Hello!
I receive an error while running the following section:
   syms V I R fR L dI Ka I w
   str2sym('V == I*(R+fR) + L*dI + Ka*I*w')
I get the error
Error using str2sym (line 213)
Unable to convert string to symbolic expression:
Error: Unexpected MATLAB expression.
After looking inside the error with dbstop if error, I found the variable 'I' is treated as special character. why so?

Best Answer

This is a bug involving use of the variables I or J or 'Pi' or 'PI' or 'pI'. Also, you cannot use if in an expression, and i and j will be translated into 1i .
Those are the only one-character and two-character variable names that are affected.
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