Matlab Symbolic output 'I' - what does it denote?

I have recently been using the symbolic toolbox to compute a series of partial derivatives for me. The outputs of the computation have non-matlab expressions so when I try to copy and evaluate the expressions I get multiple errors (i can't use 'sub' or or other symbolic toolbox methods of evaluation because it takes too long for my application). I am in the process of changing those expressions to matlab functions (i.e. Im - imag, Re-real) and I have encountered an 'I' term in the output expression. It is not the imaginary 'i' because that also exists in the expression and it is scalar therefore it can't be the identity matrix.....does anyone know what it denotes?

[Walter Roberson]

I suggest trying matlabFunction() to convert the symbolic expression for you.

Answer 1

[Walter Roberson]

"I" is the square root of negative one for the symbolic engine.

If you also have "i" in the expression, you probably had a string which you evaluated by the symbolic engine in which you attempted to use "i" in the string: in strings that are evaluated by the symbolic engine, you need to use "I" instead.