Package transsys :: Module optim :: Class LowerBoundedFunction

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Class LowerBoundedFunction

            object --+    
                     |    
TransformationFunction --+
                         |
                        LowerBoundedFunction

A function asymptoting to a finite lower bound as x -> -Inf and linearly diverging as x -> +Inf.

This implements the function 0.5 * x + sqrt(1.0 + 0.25 * x^2), which approaches 1/x for small x and x for large x. Like arctan, this function approaches its asymptote with O(1/x) and may therefore be favourable over exponential functions. Linear divergence may also be much less prone to extremes than exponential divergence.

Instance Methods

__init__(self, minValue=0.0)
x.__init__(...) initializes x; see x.__class__.__doc__ for signature

source code

__call__(self, x)
Compute the transformed value of x. source code

__str__(self)
str(x)

source code

parse_variables(self, f)

source code

clip(self, y)
Clip y to the nearest admissible value. source code

inverse(self, y)
Compute the inverse value of y. source code

Inherited from TransformationFunction: check_savefile_magic, parse

Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__

Class Variables

functionName = 'LowerBoundedFunction'

Properties

Inherited from object: __class__

Method Details

init(self, minValue=0.0)
(Constructor)

x.__init__(...) initializes x; see x.__class__.__doc__ for signature

Overrides: object.__init__: (inherited documentation)

call(self, x)
(Call operator)

Compute the transformed value of x.

Overrides: TransformationFunction.__call__: (inherited documentation)

str(self)
(Informal representation operator)

str(x)

Overrides: object.__str__: (inherited documentation)

parse_variables(self, f)

Overrides: TransformationFunction.parse_variables

clip(self, y)

Clip y to the nearest admissible value.

Overrides: TransformationFunction.clip: (inherited documentation)

inverse(self, y)

Compute the inverse value of y.

This method should return the untransformed value x corresponding to y, such that f(x) = y.

Overrides: TransformationFunction.inverse: (inherited documentation)