Finite Difference Derivative

Estimate the derivative $f^{\mathrm{\prime }}(x)f\text{'}(x)$ of a scalar function at a point with a centered finite difference and step h.

Implement solve(f, x, h=1e-5).

Returns. Return a float.

Examples

Example 1

Input:

solve(lambda t: t**2, 3.0)

Output:

6.0

Example 2

Input:

solve(lambda t: t**3, 2.0)

Output:

12.0