SecantSolver

class hoomd.tune.SecantSolver(gamma=0.9, tol=1e-05)

Bases: RootSolver

Solves equations of f(x) = y using the secant method.

The solver updates x each step via,

$$x_n = x - \gamma \cdot (y - t) \cdot \frac{x - x_{o}}{y - y_{old}}$$

where $o$ represent the old values, $n$ the new, and $t$ the target. Due to the need for a previous value, then first time this is called it makes a slight jump higher or lower to start the method.

The solver will stop updating when $\lvert y - t \rvert \le tol$.

Parameters:

• gamma (float, optional) – real number between 0 and 1 used to dampen the rate of change in x. gamma scales the corrections to x each iteration. Larger values of gamma lead to larger changes while a gamma of 0 leads to no change in x at all.

• tol (float, optional) – The absolute tolerance for convergence of y, defaults to 1e-5.

Note

Tempering the solver with a smaller than 1 gamma value is crucial for numeric stability. If instability is found, then lowering gamma accordingly should help.

__eq__(other)

Test for equality.

reset()

Reset all solving internals.

solve_one(tunable)

Solve one step.