## SymPy – 17 – calcolo infinitesimale – 3 Continuo da qui, copio qui.

Limiti
SymPy can compute symbolic limits with the `limit` function. The syntax to compute is `limit(f(x), x, x0)`. `limit` should be used instead of `subs` whenever the point of evaluation is a singularity. Even though SymPy has objects to represent `∞`, using them for evaluation is not reliable because they do not keep track of things like rate of growth. Also, things like `∞-∞` and `∞/∞` return `NaN` (not-a-number). For example Like `Derivative` and `Integral`, `limit` has an unevaluated counterpart, `Limit`. To evaluate it, use `doit`. To evaluate a limit at one side only, pass `'+'` or `'-'` as a third argument to `limit`. For example, to compute do Espansione di serie
SymPy can compute asymptotic series expansions of functions around a point. To compute the expansion of `f(x)` around the point `x=x0` terms of order `xn`, use `f(x).series(x, x0, n)`. `x0` and `n` can be omitted, in which case the defaults `x0=0` and `n=6` will be used. The `O(x4)` term at the end represents the Landau order term at `x=0` (not to be confused with `big O` notation used in computer science, which generally represents the Landau order term at `x=∞`). It means that all `x` terms with power greater than or equal to `x4` are omitted. Order terms can be created and manipulated outside of series. They automatically absorb higher order terms. If you do not want the order term, use the `removeO` method. The `O` notation supports arbitrary limit points (other than `0`): Aggiornamento: il capitolo continua con Finite differences ma semplicemente non funziona 😡
Le funzioni risultano non definite; Stack Overflow ha diversi post a riguardo, tutti segnalantio problemi. Salto 😜 Forse in futuro… 😉

Aggiornamento 2: era solo la versione da aggiornare; non leggete l’aggiornamento precedente, quello scancellato 😉 Posta un commento o usa questo indirizzo per il trackback.