Asymptotic Expansions — Miscellaneous¶
AUTHORS:
Daniel Krenn (2015)
ACKNOWLEDGEMENT:
Benjamin Hackl, Clemens Heuberger and Daniel Krenn are supported by the Austrian Science Fund (FWF): P 24644-N26.
Benjamin Hackl is supported by the Google Summer of Code 2015.
Functions, Classes and Methods¶
- class sage.rings.asymptotic.misc.Locals¶
Bases:
dictA frozen dictionary-like class for storing locals of an
AsymptoticRing.EXAMPLES:
sage: from sage.rings.asymptotic.misc import Locals sage: locals = Locals({'a': 42}) sage: locals['a'] 42
The object contains default values (see
default_locals()) for some keys:sage: locals['log'] <function log at 0x...>
- default_locals()¶
Return the default locals used in the
AsymptoticRing.OUTPUT:
A dictionary.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import Locals sage: locals = Locals({'a': 2, 'b': 1}) sage: locals {'a': 2, 'b': 1} sage: locals.default_locals() {'log': <function log at 0x...>} sage: locals['log'] <function log at 0x...>
- exception sage.rings.asymptotic.misc.NotImplementedBZero(asymptotic_ring=None, var=None, exact_part=0)¶
Bases:
NotImplementedErrorA special NotImplementedError which is raised when the result is B(0) which means 0 for sufficiently large values of the variable.
- exception sage.rings.asymptotic.misc.NotImplementedOZero(asymptotic_ring=None, var=None, exact_part=0)¶
Bases:
NotImplementedErrorA special NotImplementedError which is raised when the result is O(0) which means 0 for sufficiently large values of the variable.
- class sage.rings.asymptotic.misc.WithLocals¶
Bases:
sage.structure.sage_object.SageObjectA class extensions for handling local values; see also
Locals.This is used in the
AsymptoticRing.EXAMPLES:
sage: A.<n> = AsymptoticRing('n^ZZ', QQ, locals={'a': 42}) sage: A.locals() {'a': 42}
- locals(locals=None)¶
Return the actual
Localsobject to be used.INPUT:
locals– an objectIf
localsis notNone, then aLocalsobject is created and returned. IflocalsisNone, then a storedLocalsobject, if any, is returned. Otherwise, an empty (i.e. no values except the default values)Localsobject is created and returned.
OUTPUT:
A
Localsobject.
- sage.rings.asymptotic.misc.bidirectional_merge_overlapping(A, B, key=None)¶
Merge the two overlapping tuples/lists.
INPUT:
A– a list or tuple (type has to coincide with type ofB).B– a list or tuple (type has to coincide with type ofA).key– (default:None) a function. IfNone, then the identity is used. Thiskey-function applied on an element of the list/tuple is used for comparison. Thus elements with the same key are considered as equal.
OUTPUT:
A pair of lists or tuples (depending on the type of
AandB).Note
Suppose we can decompose the list \(A=ac\) and \(B=cb\) with lists \(a\), \(b\), \(c\), where \(c\) is nonempty. Then
bidirectional_merge_overlapping()returns the pair \((acb, acb)\).Suppose a
key-function is specified and \(A=ac_A\) and \(B=c_Bb\), where the list of keys of the elements of \(c_A\) equals the list of keys of the elements of \(c_B\). Thenbidirectional_merge_overlapping()returns the pair \((ac_Ab, ac_Bb)\).After unsuccessfully merging \(A=ac\) and \(B=cb\), a merge of \(A=ca\) and \(B=bc\) is tried.
- sage.rings.asymptotic.misc.bidirectional_merge_sorted(A, B, key=None)¶
Merge the two tuples/lists, keeping the orders provided by them.
INPUT:
A– a list or tuple (type has to coincide with type ofB).B– a list or tuple (type has to coincide with type ofA).key– (default:None) a function. IfNone, then the identity is used. Thiskey-function applied on an element of the list/tuple is used for comparison. Thus elements with the same key are considered as equal.
Note
The two tuples/list need to overlap, i.e. need at least one key in common.
OUTPUT:
A pair of lists containing all elements totally ordered. (The first component uses
Aas a merge base, the second componentB.)If merging fails, then a RuntimeError is raised.
- sage.rings.asymptotic.misc.combine_exceptions(e, *f)¶
Helper function which combines the messages of the given exceptions.
INPUT:
e– an exception.*f– exceptions.
OUTPUT:
An exception.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import combine_exceptions sage: raise combine_exceptions(ValueError('Outer.'), TypeError('Inner.')) Traceback (most recent call last): ... ValueError: Outer. > *previous* TypeError: Inner. sage: raise combine_exceptions(ValueError('Outer.'), ....: TypeError('Inner1.'), TypeError('Inner2.')) Traceback (most recent call last): ... ValueError: Outer. > *previous* TypeError: Inner1. > *and* TypeError: Inner2. sage: raise combine_exceptions(ValueError('Outer.'), ....: combine_exceptions(TypeError('Middle.'), ....: TypeError('Inner.'))) Traceback (most recent call last): ... ValueError: Outer. > *previous* TypeError: Middle. >> *previous* TypeError: Inner.
- sage.rings.asymptotic.misc.log_string(element, base=None)¶
Return a representation of the log of the given element to the given base.
INPUT:
element– an object.base– an object orNone.
OUTPUT:
A string.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import log_string sage: log_string(3) 'log(3)' sage: log_string(3, base=42) 'log(3, base=42)'
- sage.rings.asymptotic.misc.parent_to_repr_short(P)¶
Helper method which generates a short(er) representation string out of a parent.
INPUT:
P– a parent.
OUTPUT:
A string.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import parent_to_repr_short sage: parent_to_repr_short(ZZ) 'ZZ' sage: parent_to_repr_short(QQ) 'QQ' sage: parent_to_repr_short(SR) 'SR' sage: parent_to_repr_short(RR) 'RR' sage: parent_to_repr_short(CC) 'CC' sage: parent_to_repr_short(ZZ['x']) 'ZZ[x]' sage: parent_to_repr_short(QQ['d, k']) 'QQ[d, k]' sage: parent_to_repr_short(QQ['e']) 'QQ[e]' sage: parent_to_repr_short(SR[['a, r']]) 'SR[[a, r]]' sage: parent_to_repr_short(Zmod(3)) 'Ring of integers modulo 3' sage: parent_to_repr_short(Zmod(3)['g']) 'Univariate Polynomial Ring in g over Ring of integers modulo 3'
- sage.rings.asymptotic.misc.repr_op(left, op, right=None, latex=False)¶
Create a string
left op rightwith taking care of parentheses in its operands.INPUT:
left– an element.op– a string.right– an element.latex– (default:False) a boolean. If set, then LaTeX-output is returned.
OUTPUT:
A string.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import repr_op sage: repr_op('a^b', '^', 'c') '(a^b)^c'
- sage.rings.asymptotic.misc.repr_short_to_parent(s)¶
Helper method for the growth group factory, which converts a short representation string to a parent.
INPUT:
s– a string, short representation of a parent.
OUTPUT:
A parent.
The possible short representations are shown in the examples below.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import repr_short_to_parent sage: repr_short_to_parent('ZZ') Integer Ring sage: repr_short_to_parent('QQ') Rational Field sage: repr_short_to_parent('SR') Symbolic Ring sage: repr_short_to_parent('NN') Non negative integer semiring sage: repr_short_to_parent('UU') Group of Roots of Unity
- sage.rings.asymptotic.misc.split_str_by_op(string, op, strip_parentheses=True)¶
Split the given string into a tuple of substrings arising by splitting by
opand taking care of parentheses.INPUT:
string– a string.op– a string. This is used by str.split. Thus, if this isNone, then any whitespace string is a separator and empty strings are removed from the result.strip_parentheses– (default:True) a boolean.
OUTPUT:
A tuple of strings.
- sage.rings.asymptotic.misc.strip_symbolic(expression)¶
Return, if possible, the underlying (numeric) object of the symbolic expression.
If
expressionis not symbolic, thenexpressionis returned.INPUT:
expression– an object
OUTPUT:
An object.
EXAMPLES:
sage: from sage.rings.asymptotic.misc import strip_symbolic sage: strip_symbolic(SR(2)); _.parent() 2 Integer Ring sage: strip_symbolic(SR(2/3)); _.parent() 2/3 Rational Field sage: strip_symbolic(SR('x')); _.parent() x Symbolic Ring sage: strip_symbolic(pi); _.parent() pi Symbolic Ring
- sage.rings.asymptotic.misc.substitute_raise_exception(element, e)¶
Raise an error describing what went wrong with the substitution.
INPUT:
element– an element.e– an exception which is included in the raised error message.
OUTPUT:
Raise an exception of the same type as
e.
- sage.rings.asymptotic.misc.transform_category(category, subcategory_mapping, axiom_mapping, initial_category=None)¶
Transform
categoryto a new category according to the given mappings.INPUT:
category– a category.subcategory_mapping– a list (or other iterable) of triples(from, to, mandatory), wherefromandtoare categories andmandatoryis a boolean.
axiom_mapping– a list (or other iterable) of triples(from, to, mandatory), wherefromandtoare strings describing axioms andmandatoryis a boolean.
initial_category– (default:None) a category. When transforming the given category, thisinitial_categoryis used as a starting point of the result. This means the resulting category will be a subcategory ofinitial_category. Ifinitial_categoryisNone, then thecategory of objectsis used.
OUTPUT:
A category.
Note
Consider a subcategory mapping
(from, to, mandatory). Ifcategoryis a subcategory offrom, then the returned category will be a subcategory ofto. Otherwise and ifmandatoryis set, then an error is raised.Consider an axiom mapping
(from, to, mandatory). Ifcategoryis has axiomfrom, then the returned category will have axiomto. Otherwise and ifmandatoryis set, then an error is raised.EXAMPLES:
sage: from sage.rings.asymptotic.misc import transform_category sage: from sage.categories.additive_semigroups import AdditiveSemigroups sage: from sage.categories.additive_monoids import AdditiveMonoids sage: from sage.categories.additive_groups import AdditiveGroups sage: S = [ ....: (Sets(), Sets(), True), ....: (Posets(), Posets(), False), ....: (AdditiveMagmas(), Magmas(), False)] sage: A = [ ....: ('AdditiveAssociative', 'Associative', False), ....: ('AdditiveUnital', 'Unital', False), ....: ('AdditiveInverse', 'Inverse', False), ....: ('AdditiveCommutative', 'Commutative', False)] sage: transform_category(Objects(), S, A) Traceback (most recent call last): ... ValueError: Category of objects is not a subcategory of Category of sets. sage: transform_category(Sets(), S, A) Category of sets sage: transform_category(Posets(), S, A) Category of posets sage: transform_category(AdditiveSemigroups(), S, A) Category of semigroups sage: transform_category(AdditiveMonoids(), S, A) Category of monoids sage: transform_category(AdditiveGroups(), S, A) Category of groups sage: transform_category(AdditiveGroups().AdditiveCommutative(), S, A) Category of commutative groups
sage: transform_category(AdditiveGroups().AdditiveCommutative(), S, A, ....: initial_category=Posets()) Join of Category of commutative groups and Category of posets
sage: transform_category(ZZ.category(), S, A) Category of commutative groups sage: transform_category(QQ.category(), S, A) Category of commutative groups sage: transform_category(SR.category(), S, A) Category of commutative groups sage: transform_category(Fields(), S, A) Category of commutative groups sage: transform_category(ZZ['t'].category(), S, A) Category of commutative groups
sage: A[-1] = ('Commutative', 'AdditiveCommutative', True) sage: transform_category(Groups(), S, A) Traceback (most recent call last): ... ValueError: Category of groups does not have axiom Commutative.