Coerce maps

class sage.structure.coerce_maps.CCallableConvertMap_class

Bases: Map

class sage.structure.coerce_maps.CallableConvertMap

Bases: Map

This lets one easily create maps from any callable object.

This is especially useful to create maps from bound methods.

EXAMPLES:

Sage

sage: from sage.structure.coerce_maps import CallableConvertMap
sage: def foo(P, x): return x/2
sage: f = CallableConvertMap(ZZ, QQ, foo)
sage: f(3)
3/2
sage: f
Conversion via foo map:
  From: Integer Ring
  To:   Rational Field

Python

>>> from sage.all import *
>>> from sage.structure.coerce_maps import CallableConvertMap
>>> def foo(P, x): return x/Integer(2)
>>> f = CallableConvertMap(ZZ, QQ, foo)
>>> f(Integer(3))
3/2
>>> f
Conversion via foo map:
  From: Integer Ring
  To:   Rational Field

Create a homomorphism from \(\RR\) to \(\RR^+\) viewed as additive groups.

Sage

sage: # needs sage.symbolic
sage: f = CallableConvertMap(RR, RR, exp, parent_as_first_arg=False)
sage: f(0)
1.00000000000000
sage: f(1)
2.71828182845905
sage: f(-3)
0.0497870683678639

Python

>>> from sage.all import *
>>> # needs sage.symbolic
>>> f = CallableConvertMap(RR, RR, exp, parent_as_first_arg=False)
>>> f(Integer(0))
1.00000000000000
>>> f(Integer(1))
2.71828182845905
>>> f(-Integer(3))
0.0497870683678639

class sage.structure.coerce_maps.DefaultConvertMap

Bases: Map

This morphism simply calls the codomain’s element_constructor method, passing in the codomain as the first argument.

EXAMPLES:

Sage

sage: QQ[['x']].coerce_map_from(QQ)
Coercion map:
  From: Rational Field
  To:   Power Series Ring in x over Rational Field

Python

>>> from sage.all import *
>>> QQ[['x']].coerce_map_from(QQ)
Coercion map:
  From: Rational Field
  To:   Power Series Ring in x over Rational Field

class sage.structure.coerce_maps.DefaultConvertMap_unique

Bases: DefaultConvertMap

This morphism simply defers action to the codomain’s element_constructor method, WITHOUT passing in the codomain as the first argument.

This is used for creating elements that don’t take a parent as the first argument to their __init__ method, for example, Integers, Rationals, Algebraic Reals… all have a unique parent. It is also used when the element_constructor is a bound method (whose self argument is assumed to be bound to the codomain).

class sage.structure.coerce_maps.ListMorphism

Bases: Map

class sage.structure.coerce_maps.NamedConvertMap

Bases: Map

This is used for creating elements via the _xxx_ methods.

For example, many elements implement an _integer_ method to convert to ZZ, or a _rational_ method to convert to QQ.

method_name

class sage.structure.coerce_maps.TryMap

Bases: Map

sage.structure.coerce_maps.test_CCallableConvertMap(domain, name=None)

For testing CCallableConvertMap_class.