verry.autodiff.deriv

verry.autodiff.deriv(fun)

Return a function that evaluates the derivative of the univariate scalar-valued function.

Parameters:

fun (Callable) – Diffarentiated function.

Returns:

Derivative of fun.

Return type:

Callable

Warning

fun must neither be a constant nor contain conditional branches (cf. Common pitfalls).

Examples

This example computes a value of the derivative.

>>> from verry import FloatInterval as FI
>>> from verry import function as vrf
>>> f = lambda x: x**2 + vrf.sqrt(x + 3)
>>> df = deriv(f)
>>> c0 = df(1.2)
>>> print(format(c0, ".6g"))
2.64398

To obtain the value that accounts for rounding errors, pass an interval to df.

>>> c1 = df(FI("1.2"))
>>> print(format(c1, ".6g"))
[2.64397, 2.64398]

Also, the second-order derivative can be obtained in the same way.

>>> ddf = deriv(df)
>>> print(format(ddf(FI("1.2")), ".6g"))
[1.97095, 1.97096]