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 Improve speed sigma_invariants is currently very slow. (Took several minutes to compute 2cycle sigma invariants for a cubic.) If we hope to use this to describe functions in the "Arithmetic Dynamics Database," then computation needs to be much faster.     Improve speed sigma_invariants is currently very slow. (Took several minutes to compute 2cycle sigma invariants for a cubic.) If we hope to use this to describe functions in the "Arithmetic Dynamics Database," then computation needs to be much faster.  Need to think about methods. Will numerical approximations go faster? Do we need to bound denominators of symmetric functions? Can we? 
Arithmetic and Complex Dynamics
The goal of sagedynamics is to improve the open source mathematical software Sage for computer exploration in dynamical systems and foster code sharing between researchers in this area. This portion focuses on the Arithmetic (Number Theoretic) and Complex aspects of dynamical systems.
News
[email protected]  Program on Computational Arithmetic Dynamics  July 25, 2016  July 29, 2016
NSF DMS1415294  Computational Tools for Dynamical Systems 9/2014  8/2017 (P.I.: Hutz)
Past News
Sage Days Held Sage Days 55 (November 710, 2013) at Florida Institute of Technology.
January 30, 2012  May 4, 2012 ICERM semeser program on Complex and Arithmetic Dynamics
How to participate and contribute
sagedynamics: Google group
 anyone may subscribe by sending an email to: sagedynamics+subscribe at googlegroups dot com
Documentation and Tutorials
sagecombinat has many excellent tutorials combinat docs
Road Map
The arithmetic and complex dynamics functionality in Sage is currently in its infancy. A significant amount of functionality was developped at the ICERM semester in Spring 2012 and now we have started the process of moving this into Sage through a series of patches (trac tickets). Most of that functionality is current in experimental for that been greatly expanded upon at Sage Days 55. Much remains to be done. Below you will find a road map of what has been implemented, what is in the process of being implemented, and ideas for future functionality.
In Progress
(#21129) needsreview: implementation of ArakelovZhang pairing for rational maps  Paul Fili, Holly Krieger
(#21118) needswork: list of degrees of iterates of function  Joseph Silverman
(#21117) needsreview: specialization for subschemes and scheme_morphisms  Ben Hutz
(#21113) needsreview: unflattening morphism error  Ben Hutz
(#21112) positivereview: wrong base ring in sigma invariants  Ben Hutz
(#21108) positivereview: use flattening in quo_rem  Vincent Delacroix
(#21106) positivereview: class for flattening morphism  Vincent Delecroix, Ben Hutz
(#21104) positivereview: indeterminancy locus  Michelle Manes
(#21100) positivereview (duplicate/won't fix): division error in normalize_coordinates  Ben Hutz
(#21099) needsreview: critical subscheme / critical points for a map on projective space  Michelle Manes
(#21097) positivereview: incorrect parent in dynatomic_polynomial  Michelle Manes
(#20227) needsreview: Chow form for projective subschemes  Ben Hutz
(#15378) Composition of Morphisms  Vincent Delecroix, Donald Richardson, Soli Vishkautsan
Eigenvalues (see #14990 and #15390) for an implementation of the algebraic closure of finite field)  Vincent Delecroix , Ben Hutz
Wishlist
 PLEASE ADD MORE...
Wishlist
Area
Description
Difficulty
Priority
Products of Projective Spaces
Rational Points on Subschemes
Implement an efficient rational points search on subschemes. Currently it is done by enumeration unless dim is 0
Polynomials
specific functionality for regular polynomial endomorphisms of P^N
Rational Maps
Dynamical degree(s), arithmetic degree
periodic and preperiodic points (projective and affine)
Q.is_iterate_defined(f,n)
Q.hits_indeterminancy_locus(f,n)
add noramlize parameter to nth_iterate_map
Q.height_iterate_sequence
cyclegraph
Numerical Precision
implement Algorithm 4 from "Computing algebraic numbers of bounded height" by DoyleKrumm to use in elements_of_bounded_height for number fields. This is a high priority since currently the precision has an effect on the output. Algorithm 4 is able to take precision into account.
Hard
High
use real interval field for floating point computations (in heights and possibly rational preperiodic point functions)
medium
Attracting Cycles
Check if for a given algebraic parameter c the map z > z^2 + c is hyperbolic... and more generally for rational maps of P1 determine the existence (and list) of attracting cycles
NonIntegral Domains
Make projective space work over nonintegral domains. One method would be to make a valid point on which is valid for modulo all maximal ideals
Documentation
Write Tutorials
Complex Dynamics
Implement Thurston's algorithm. More precisely, develop an efficient method to determine if there is a Thurston obstruction. (Epstein, ICERM)
Dynamical Zeta Functions
Compute the dynamical zeta function
Miscellaneous
Implement a function which takes as input to rational functions f(x) and g(x), and determines whether or not f^n=g^m for some integers n,m \geq 1. (Zieve, ICERM)
Coercion
some kind of coercion model: if you have a map defined over QQ should you be able to take the image of a point over CC (i.e. somewhere you have a well defined embedding) without having to change_ring(). Something like this works for polynomials. This may or may not be a good idea, but if it can be done in a consistent manner it would improve usability in certain situations.
Postcritically finite morphisms
given a number field enumerate pcf maps over that field
given a graph, find a pcf map with that graph (approximate with spider algorithm or exact?)
given a family, which members are pcf
Berkovich P1
Improve speed
sigma_invariants is currently very slow. (Took several minutes to compute 2cycle sigma invariants for a cubic.) If we hope to use this to describe functions in the "Arithmetic Dynamics Database," then computation needs to be much faster.
Need to think about methods. Will numerical approximations go faster? Do we need to bound denominators of symmetric functions? Can we?
Complete
#21091 closed sage 7.3: is_polynomial bug fix  Ben Hutz
#20820 closed sage 7.3: Conjugating sets of Rational Functions  Rebecca Lauren Miller
#20780 closed sage 7.3: add level parameter to rational_preimages  Ben Hutz
#20650 closed sage 7.3: Added is_polynomial and make_look_poly to projective morphism  Rebecca Lauren Miller, Ben Hutz
#19635 closed sage 7.3: Enumeration functionality for products of projective spaces over fields and finite fields  Grayson Jorgenson
#20079 closed sage 7.3: Chebyshev Polynomials  Joe Eisner, Ben Hutz
#20451 closed sage 7.2: canonical height error  Ben Hutz
#20262 closed sage 7.2: Add point transformation matrix for projective space  Rebecca Lauren Miller
#20168 closed sage 7.2: small improvements to projective morphism  Ben Hutz
#20059 closed sage 7.1: minimal periodic points code improvement  Ben Hutz
#20067 closed sage 7.1: Change ring to QQbar fails for subschemes  Ben Hutz
#20018 closed sage 7.1: init for endomorphism of projective subschemes fails  Ben Hutz
#19979 closed sage 7.1: Fix coding style and documentation in projective products  Rebecca Lauren Miller
#19889 closed sage 7.1: Fix coding style and documentation style in affine schemes  Rebecca Lauren Miller
#19991 closed sage 7.1: improve dimension function for subschemes of projective products  Ben Hutz
#19891 closed sage 7.1: Fix coding style and documentation in Projective schemes  Ben Hutz
#19551 closed sage 7.0: Basic failures in projective product morphisms  Ben Hutz
#19552 closed sage 7.0: images and preimages of projective subschemes  Ben Hutz
#19557 closed sage 6.10: Basic iteration functionality for products of projective spaces  Grayson Jorgenson
#19512 closed sage 6.10: is_morphism for maps of products of projective spaces  Grayson Jorgenson
#18443 closed sage 6.8: Multiplier spectra for projective morphisms  Grayson Jorgenson
#18374 closed sage 6.8: Inconsistency in dimension of total ideals.  Miguel Marco
#18281 closed sage 6.8: implement critical point functionality including is_pcf for projective morphisms  Ben Hutz
#17282 closed sage 6.8: Implementing Wehler K3 Surfaces  Joao Faria
#18409 closed sage 6.8: Dynatomic polynomial bug for fractional coefficients  Ben Hutz
#18399 closed sage 6.8: projective automorphism group fails for homogenized maps  Ben Hutz
#18279 closed sage 6.7: implement rational preperiodic points for polynomials over number fields  Ben Hutz
#18008 closed sage 6.7: Periodic points for projective/affine morphism  Grayson Jorgenson
#17855 closed sage 6.7: create is_preperiodic function for points of projective space  Ben Hutz
#17907 closed sage 6.6: Random failure in enum_projective_number_field  Ben Hutz
#17729 closed sage 6.6: Implement Weil restriction for affine schemes/points/morphisms  Ben Hutz
#17762 closed sage 6.6: Connected component for a rational preperiodic point  Grayson Jorgenson
#17323 closed sage 6.6: Implement "primes_of_bad_reduction" to work over Number Fields  Joao Faria
#17386 closed sage 6.6: Enumerate points of bounded height in projective/affine space over number fields  Grayson Jorgenson
#17326 closed sage 6.6: Implementing subschemes functionality for projective "is_morphism"  Joao Faria
#17067 closed sage 6.5: Enabled canonical height for maps of \PP^N over number fields  Ben Hutz, Paul Fili
#15393 closed sage 6.5: FMV Algorithm for automorphism groups  Bianca Thompson, Ben Hutz, Joao Faria
#17082 closed sage 6.5: Height Difference Bounds over number fields  Joao Faria
#17427 closed sage 6.5: x==y while hash(x)!=hash(y) with SchemeMorphism_point_projective_field  Ben Hutz
#17535 closed sage 6.5: Homogenize fails for affine space over function fields  Ben Hutz
#17433 closed sage 6.5: projective point equality fails for quoteint base rings  Ben Hutz
#17441 closed sage 6.5: Change ring fails for SchemeMorphism_polynomial defined with fraction field elements  Grayson Jorgenson
#17325 closed sage 6.5: clear denominators for projective points does not always work  Joao Faria
#17450 closed sage 6.5: Fix category for quotients of polynomial rings  Travis Scrimshaw
#17429 closed sage 6.5: projective point equality returns false positive for ComplexIntervalField  Ben Hutz
#17324 closed sage 6.5: implement eq and ne for affine morphisms  Ben Hutz
#15448 closed sage 6.5: cartesian products of projective space  Ben Hutz
#16986 closed sage 6.5: Rational Preimages and All Rational Preimages over number fields  Joao Faria
#17118 closed sage 6.4: Added multiplier computation to affine morphism  Grayson Jorgenson
#17001 closed sage 6.4: Functionality for fast evaluation of affine morphisms  Grayson Jorgeson
#16961 closed sage 6.4: Fix Dynatomic Polynomials to work over the Complex Numbers  Joao de Faria
#16960 closed sage 6.4: Orbit Structure for Affine Morphisms  Grayson Jorgenson
#16838 closed sage 6.4: make affine and projective dehomogenize and homogenize work together  Ben Hutz
#16833 closed sage 6.4: Use Macaulay resultant to compute resultant of projective morphisms  Joao de Faria
#16834 closed sage 6.4: Change ring fails for affine morphisms  Grayson Jorgenson
#16832 closed sage 6.4: Can't Coerce projective point to subscheme point  Peter Bruin
#15394 closed sage 6.4: Lattes map from an Elliptic Curve  Patrick Ingram, Ben Hutz
#15389 closed sage.6.3: KrummDoyle Small Points Algorithm  David Krumm, John Doyle
#15382 closed sage.6.3: MacCaulay Resultant  Soli Vishkautsan, Hao Chen
#15782 closed sage.6.3: Increase Performance of Multiplier in Projective Morphism  Dillon Rose and Ben Hutz
#15781 closed sage.6.3: Increase Performance of possible_periods in Projective Morphism  Dillon Rose and Ben Hutz
#15780 closed sage.6.3: Increase Performance in Projective Morphism  Dillon Rose
#16168 closed sage.6.3: use p_iter_fork in projective_morphism  Dillon Rose
#16051 closed sage.6.3: fast_callable can return ipow with exponents in the base ring  Ben Hutz
#15920 closed sage.6.2: Parallelize Possible Periods functions for Projective Morphisms  Dillon Rose
#15815 closed sage.6.2: rational preimages for projective morphisms returns incorrect points  Ben Hutz
#15490 closed sage.6.2: documentation fix for projective dynatomic polynomials  Weixin Wu
#15396 closed sage.6.1: Implement .an_element() for ProjectiveSpace  Ben Hutz
#15392 closed sage.5.13.rc0: BruinMolnar Algorithm for minimal models  Brian Stout, Ben Hutz
#15376 closed sage5.13.beta4: canonical heights for points with integer fix  Paul Fili
#14219 closed sage5.13.beta4: Rational preperiodic points  Ben Hutz
#15373 closed sage5.13.beta3: Global height for integer fix  Paul Fili
#15377 closed sage5.13.beta3: improve documentation of normalize_coordinates  Ben Hutz
#14218 closed sage5.13.beta2: Height and canonical heights for points and morphisms  Ben Hutz
#14217 closed sage5.10.beta3: Basic iteration functionality for projective and affine spaces  new directory structure in schemes  Ben Hutz
#13130 closed sage5.8.beta3: Basic architecture changes : support for projective spaces over rings  Ben Hutz