# how to tell if a function is admissible as a 'symbolic' function

Sorry for the wording of the question. Functions in sage.functions.special, such as airy_ai, seem not to be true functions, e.g. you can't apply taylor() to them. On the other hand, maxima.airy_ai seems to be OK. How can I tell what "status" a function has, or whether I can pass it to operations such as taylor()?

```
taylor(maxima.airy_ai(x),x,0,4)
```

-1/36*3^(2/3)*x^4/gamma(1/3) + 1/18*3^(1/3)*x^3/gamma(2/3) -
1/3*3^(2/3)*x/gamma(1/3) + 1/3*3^(1/3)/gamma(2/3)

```
taylor(sage.functions.special.airy_ai(x),x,0,4)
```

Traceback (click to the left of this block for traceback) ... TypeError: Cannot evaluate symbolic expression to a numeric value.