atsim.potentials._util

Module Contents

Functions

deriv(r, func, h=1e-06)	Evaluates the derivative of a unary callable, func at a value of r.
num_deriv(r, func, h=1e-06)	Returns numerical derivative of the callable func
gradient(func, h=1e-06)	Function wrapper that returns derivative of func.

atsim.potentials._util.deriv(r, func, h=1e-06)

Evaluates the derivative of a unary callable, func at a value of r.

If the object func has a unary method deriv(r), this will be used to evauluate the derivative (allowing analytical derivatives to be used).

If func does not have a specific deriv(r) method then its numerical-derivative of will be taken by calling num_deriv()

Parameters:

• r – Value at which derivative of func should be evaluated.
• func – Function whose derivative is to be evaluated.
• h – Step size used when performing numerical differentiation.

Returns:

Derivative of func at r.

atsim.potentials._util.num_deriv(r, func, h=1e-06)

Returns numerical derivative of the callable func

Parameters:

• r – Value at which derivative of func should be evaluated.
• func – Function whose gradient is to be evaluated.
• h – Step size used when performing numerical differentiation.

Returns:

Numerical derivative of func at r.

atsim.potentials._util.gradient(func, h=1e-06)

Function wrapper that returns derivative of func.

If the callable, func provides a .deriv(r) method this will be used to evaluate the derivative of the function, if not the returned function will use num_deriv() in gradient evaluation.

If the callable additionally provides a .deriv2(r) method, representing its second derivative, the function returned by this routine will have a deriv() method which will delegate to func.deriv2() when called.

By providing .deriv() and .deriv2() on the func callable analytical descriptions of a potential’s first and second derivatives may be specified.

Parameters:

• func – Function to be wrapped
• h – Step size used when performing numerical differentiation

Returns:

Function that returns derivative of func