#17601: Meta ticket: Asymptotic Expansions in SageMath
-------------------------------------+-------------------------------------
       Reporter:  behackl            |        Owner:
           Type:  enhancement        |       Status:  new
       Priority:  major              |    Milestone:  sage-6.9
      Component:  asymptotic         |   Resolution:
  expansions                         |    Merged in:
       Keywords:  asymptotics,       |    Reviewers:
  gsoc15                             |  Work issues:
        Authors:  Benjamin Hackl,    |       Commit:
  Daniel Krenn                       |  1109ce002874d776617102f2ccc295b410e4a3b6
Report Upstream:  N/A                |     Stopgaps:
         Branch:                     |
  u/dkrenn/asy/prototype             |
   Dependencies:  #17600, #17693,    |
  #17715, #17716, #18182, #18222,    |
  #18223, #18586, #18587, #18930,    |
  #19017, #19028, #19047, #19048,    |
  #19068, #19073, #19079, #19083,    |
  #19094, #19110, #19259, #19269,    |
  #19300, #19305, #19306             |
-------------------------------------+-------------------------------------
Description changed by dkrenn:

Old description:

> We intend to implement asymptotic expansions in !SageMath. We would like
> to do computations with simple expansions such as
>
> n^2^ + n^3/2^ + O(n^1/2^),
>
> but also with expansions such as
>
> 2^n^ * n + O(n*log(n))
>
> or even multivariate expansions such as
>
> 3*k/n + O(k^2^ / n^2^) with |k| <= n^(1/2)^.
>
> Of course, O(n) - O(n) = O(n) must hold and we want to perform various
> arithmetic operations with these asymptotic expansions. Eventually,
> specified O-constants shall also be supported.
>
> -------
>
> See #17716 and #19083 for more examples and the documentation files there
> for a more detailed description. A working prototype can be found in
> branch `u/dkrenn/asy/prototype`.
> -------
>
> **Roadmap**:
>

> * Implementing a minimal working example
>     * #17600 (!AsymptoticGrowthElement): elements which handle the
> asymptotic growth. Such an element holds, e.g. n^2^ or k/n or n*log(n).
> This can compare, multiply etc., but has **no** coefficient; the order of
> magnitude is managed here. Concretely for this ticket:
> !MonomialGrowthElement, implementation for powers.
>     * #18930: Factory for user-friendly generation of growth groups
>     * #17715 (!AsymptoticTerm): a summand for asymptotic expansions. They
> contain the growth and additional information on the type of the summand.
> For starters, there will be big-Oh terms (e.g. `O(n)` and exact terms
> (e.g. `3*n^2`).
>     * #17693 (!MutablePoset): data structure for storing asymptotic terms
> within an asymptotic expansions.
>     * #17716 (!AsymptoticRing and !AsymptoticExpansion): sum of
> asymptotic terms.
>
> * Extending the functionality of growth groups
>     * #18587: cartesian products for growth groups (allowing the
> construction of more complicated univariate as well as multivariate
> asymptotic expansions)
>         * #18223: cartesian products with orders
>         * #18586: passing on parameters and extra_category for cartesian
> products
>     * #19028: More growth group implementations: exponential growth
> groups.
>
> * Extending the functionality of the !AsymptoticRing and
> !AsymptoticExpansion
>     * #19048: `AsymptoticRing.an_element()`
>         * #19047: `QQ.some_elements()`
>     * #19068: Implement Division for asymptotic expansions.
>     * #19073: categorial constructions, pushout and coercions (extended)
> for asymptotic ring and growth groups
>         * #18182: pushout construction and finding common parents
> for/including cartesian products
>         * #19079: !ConstructionFunctor: remove `__str__`
>     * #19094: Implement higher-order operations like `exp` and `log` for
> asymptotic expansions.
>     * #19083: !AsymptoticRing: cleanup, some improvements, documentation.
>
> * Further plans
>     * for growth groups
>         * implement dependencies like |k| <= n^1/2^ for different growth
> group variables.
>         * growth groups with asymptotic at a non-infinity point
>     * other
>         * Deal with comparison for asymptotic expansions.
>         * Check and improve the performance of computations in the
> !AsymptoticRing.
>         * Implementation of more types of asymptotic terms (little-oh
> terms, omega-terms, variations of big-Oh terms ...)
>         * #19300: Run benchmarks on `MutablePoset.remove` to decide
> between two algorithms.
>         * #19305: substitution of asymptotic expansions
>         * #19306: common generators for asymptotic expansions
>
> * Additional dependencies
>     * #19017: Easy access to the `O`-constructor in `big_oh.py`.
>     * #19110: QQ(0)^-1^ raises SIGFPE (which is caught)
>
> * Other related Tickets:
>     * #18222: provide <=, <, >=, > for poset elements by the category
> (depends on #10130)
>     * #19269: add category Posets to ZZ and QQ
>     * #19259: subrings of the symbolic ring

New description:

 We intend to implement asymptotic expansions in !SageMath. We would like
 to do computations with simple expansions such as

 n^2^ + n^3/2^ + O(n^1/2^),

 but also with expansions such as

 2^n^ * n + O(n*log(n))

 or even multivariate expansions such as

 3*k/n + O(k^2^ / n^2^) with |k| <= n^(1/2)^.

 Of course, O(n) - O(n) = O(n) must hold and we want to perform various
 arithmetic operations with these asymptotic expansions. Eventually,
 specified O-constants shall also be supported.

 -------

 See #17716 and #19083 for more examples and the documentation files there
 for a more detailed description. A working prototype can be found in
 branch `u/dkrenn/asy/prototype`.
 -------

 **Roadmap**:


 * Implementing a minimal working example
     * #17600 (!AsymptoticGrowthElement): elements which handle the
 asymptotic growth. Such an element holds, e.g. n^2^ or k/n or n*log(n).
 This can compare, multiply etc., but has **no** coefficient; the order of
 magnitude is managed here. Concretely for this ticket:
 !MonomialGrowthElement, implementation for powers.
     * #18930: Factory for user-friendly generation of growth groups
     * #17715 (!AsymptoticTerm): a summand for asymptotic expansions. They
 contain the growth and additional information on the type of the summand.
 For starters, there will be big-Oh terms (e.g. `O(n)` and exact terms
 (e.g. `3*n^2`).
     * #17693 (!MutablePoset): data structure for storing asymptotic terms
 within an asymptotic expansions.
     * #17716 (!AsymptoticRing and !AsymptoticExpansion): sum of asymptotic
 terms.

 * Extending the functionality of growth groups
     * #18587: cartesian products for growth groups (allowing the
 construction of more complicated univariate as well as multivariate
 asymptotic expansions)
         * #18223: cartesian products with orders
         * #18586: passing on parameters and extra_category for cartesian
 products
     * #19028: More growth group implementations: exponential growth
 groups.

 * Extending the functionality of the !AsymptoticRing and
 !AsymptoticExpansion
     * #19048: `AsymptoticRing.an_element()`
         * #19047: `QQ.some_elements()`
     * #19068: Implement Division for asymptotic expansions.
     * #19073: categorial constructions, pushout and coercions (extended)
 for asymptotic ring and growth groups
         * #18182: pushout construction and finding common parents
 for/including cartesian products
         * #19079: !ConstructionFunctor: remove `__str__`
     * #19094: Implement higher-order operations like `exp` and `log` for
 asymptotic expansions.
     * #19083: !AsymptoticRing: cleanup, some improvements, documentation.

 * Further plans
     * for growth groups
         * implement dependencies like |k| <= n^1/2^ for different growth
 group variables.
         * growth groups with asymptotic at a non-infinity point
     * other
         * Deal with comparison for asymptotic expansions.
         * Check and improve the performance of computations in the
 !AsymptoticRing.
         * Implementation of more types of asymptotic terms (little-oh
 terms, omega-terms, variations of big-Oh terms ...)
         * #19300: Run benchmarks on `MutablePoset.remove` to decide
 between two algorithms.
         * #19305: substitution of asymptotic expansions
         * #19306: common generators for asymptotic expansions
             * #19259: subrings of the symbolic ring

 * Additional dependencies
     * #19017: Easy access to the `O`-constructor in `big_oh.py`.
     * #19110: QQ(0)^-1^ raises SIGFPE (which is caught)

 * Other related Tickets:
     * #18222: provide <=, <, >=, > for poset elements by the category
 (depends on #10130)
     * #19269: add category Posets to ZZ and QQ

--

--
Ticket URL: <http://trac.sagemath.org/ticket/17601#comment:49>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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