Symbolic variable/expression in octave value list

[Shamika Mohanan]

What is the right way to access symbolic expressions in octave value list?

I have the following code-

in = octave_value ('s');
octave_value_list out =feval ("tf", in, 1);
std::cout << out(0).string_value()<< std::endl;

This shows the error-

error: octave_base_value::convert_to_str_internal (): wrong type argument '<unknown type>'

Is there an equivalent like 'is_double_type()' for symbolic expressions?

Regards,

Shamika