ScaleSolver¶

class hoomd.tune.ScaleSolver(max_scale=2.0, gamma=2.0, correlation='positive', tol=1e-05)¶

Solves equations of f(x) = y using a ratio of y with the target.

Each time this solver is called it takes updates according to the following equation if the correlation is positive:

\[x_n = \min{\left(\frac{\gamma + t}{y + \gamma}, s_{max}\right)} \cdot x\]

and

\[x_n = \min{\left(\frac{y + \gamma}{\gamma + t}, s_{max}\right)} \cdot x\]

if the correlation is negative, where \(t\) is the target and \(x_n\) is the new x.

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

Parameters:

max_scale (float, optional) – The maximum amount to scale the current x value with, defaults to 2.0.
gamma (float, optional) – nonnegative real number used to dampen or increase the rate of change in x. gamma is added to the numerator and denominator of the y / target ratio. Larger values of gamma lead to smaller changes while a gamma of 0 leads to scaling x by exactly the y / target ratio.
correlation (str, optional) – Defines whether the relationship between x and y is of a positive or negative correlation, defaults to ‘positive’. This determines which direction to scale x in for a given y.
tol (float, optional) – The absolute tolerance for convergence of y, defaults to 1e-5.

Note

This solver is only usable when quantities are strictly positive.