Re: [sympy] Using the mechanics API

[Vishesh Mangla]

Ok but still if you get a specific requirement do let me know.

On Wed, May 15, 2019, 04:59 Oscar Benjamin 
wrote:

> Hi Vishesh,
>
> I have no plans to work on anything here but of course you can feel
> free to contribute. Take a look at the module and see if there is
> something that you think can be improved. There's always something
> that can be improved so it's just a question of finding something that
> is worth doing and that you can do yourself.
>
> --
> Oscar
>
> On Mon, 13 May 2019 at 21:48, Vishesh Mangla 
> wrote:
> >
> > Hey,I also love physics and math and would like to work on the changes
> which you want to include.Can I get included in this?I ‘ve chemistry as my
> subject in university but that too deals with a lot of physics Hermitian
> mostly but I know lagrangian too.So please let me make it. If you remember
> you helped me merge my first pull request but still one was not enough to
> get me enough experience to get good with it and I require help to get a
> few more merged.
> >
> >
> >
> > Sent from Mail for Windows 10
> >
> >
> >
> > From: Oscar Benjamin
> > Sent: 14 May 2019 02:12
> > To: sympy
> > Subject: [sympy] Using the mechanics API
> >
> >
> >
> > Hi all,
> >
> >
> >
> > I haven't really looked much at SymPy's mechanics module even though
> >
> > mechanics is very much one of my interests and something that I like
> >
> > to think I know a bit about. Today I finally took a look at it and I
> >
> > found the whole API surprisingly complicated. I teach mechanics to
> >
> > undergraduate students but I'm not sure if I would know how to teach
> >
> > my students to use the mechanics module as it is now...
> >
> >
> >
> > Firstly I looked through the documentation here:
> >
> > https://docs.sympy.org/latest/modules/physics/mechanics/index.html
> >
> > Is there any other guide/documentation that explains the general ideas
> >
> > more simply with examples?
> >
> >
> >
> > Suppose that I want to think about a simple 2D problem with a disc
> >
> > rolling down a surface inclined at angle beta with (Coulomb) friction
> >
> > coefficient mu. I want to know when/whether the disc will stick or
> >
> > slip and get the equations of motion for each case. How would I go
> >
> > about doing that using the mechanics module?
> >
> >
> >
> > --
> >
> > Oscar
> >
> >
> >
> > --
> >
> > You received this message because you are subscribed to the Google
> Groups "sympy" group.
> >
> > To unsubscribe from this group and stop receiving emails from it, send
> an email to sympy+unsubscr...@googlegroups.com.
> >
> > To post to this group, send email to sympy@googlegroups.com.
> >
> > Visit this group at https://groups.google.com/group/sympy.
> >
> > To view this discussion on the web visit
> https://groups.google.com/d/msgid/sympy/CAHVvXxQXtAd_HGwTqaKrpDqQC_mNcyZAFgPrVe8Sq_hPwT6H0w%40mail.gmail.com
> .
> >
> > For more options, visit https://groups.google.com/d/optout.
> >
> >
> >
> > --
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> .
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>
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Re: [sympy] Using the mechanics API

[Oscar Benjamin]

Hi Vishesh,

I have no plans to work on anything here but of course you can feel
free to contribute. Take a look at the module and see if there is
something that you think can be improved. There's always something
that can be improved so it's just a question of finding something that
is worth doing and that you can do yourself.

--
Oscar

On Mon, 13 May 2019 at 21:48, Vishesh Mangla  wrote:
>
> Hey,I also love physics and math and would like to work on the changes which 
> you want to include.Can I get included in this?I ‘ve chemistry as my subject 
> in university but that too deals with a lot of physics Hermitian mostly but I 
> know lagrangian too.So please let me make it. If you remember you helped me 
> merge my first pull request but still one was not enough to get me enough 
> experience to get good with it and I require help to get a few more merged.
>
>
>
> Sent from Mail for Windows 10
>
>
>
> From: Oscar Benjamin
> Sent: 14 May 2019 02:12
> To: sympy
> Subject: [sympy] Using the mechanics API
>
>
>
> Hi all,
>
>
>
> I haven't really looked much at SymPy's mechanics module even though
>
> mechanics is very much one of my interests and something that I like
>
> to think I know a bit about. Today I finally took a look at it and I
>
> found the whole API surprisingly complicated. I teach mechanics to
>
> undergraduate students but I'm not sure if I would know how to teach
>
> my students to use the mechanics module as it is now...
>
>
>
> Firstly I looked through the documentation here:
>
> https://docs.sympy.org/latest/modules/physics/mechanics/index.html
>
> Is there any other guide/documentation that explains the general ideas
>
> more simply with examples?
>
>
>
> Suppose that I want to think about a simple 2D problem with a disc
>
> rolling down a surface inclined at angle beta with (Coulomb) friction
>
> coefficient mu. I want to know when/whether the disc will stick or
>
> slip and get the equations of motion for each case. How would I go
>
> about doing that using the mechanics module?
>
>
>
> --
>
> Oscar
>
>
>
> --
>
> You received this message because you are subscribed to the Google Groups 
> "sympy" group.
>
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to sympy+unsubscr...@googlegroups.com.
>
> To post to this group, send email to sympy@googlegroups.com.
>
> Visit this group at https://groups.google.com/group/sympy.
>
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/sympy/CAHVvXxQXtAd_HGwTqaKrpDqQC_mNcyZAFgPrVe8Sq_hPwT6H0w%40mail.gmail.com.
>
> For more options, visit https://groups.google.com/d/optout.
>
>
>
> --
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Re: [sympy] Using the mechanics API

[Jason Moore]

Oscar,

This is the main tutorial:
https://github.com/pydy/pydy-tutorial-human-standing

Jason
moorepants.info
+01 530-601-9791


On Tue, May 14, 2019 at 3:00 PM Oscar Benjamin 
wrote:

> Thanks Jason. Those links helped.
>
> I guess if the module is not intended for simpler problems then that
> makes sense. I would say though that the documentation could benefit
> from more of a tutorial somewhere.
>
> I'll try to use it for a real problem at some point and then see what I
> think...
>
> --
> Oscar
>
> On Tue, 14 May 2019 at 18:32, Jason Moore  wrote:
> >
> > Oscar,
> >
> > Also a specific answer to:
> >
> > > Suppose that I want to think about a simple 2D problem with a disc
> > rolling down a surface inclined at angle beta with (Coulomb) friction
> > coefficient mu. I want to know when/whether the disc will stick or
> > slip and get the equations of motion for each case. How would I go
> > about doing that using the mechanics module?
> >
> > This is way too simple of a problem to really use the mechanics module
> for. If I were teaching this I would just use the base sympy features to do
> the math. The mechanics module is not really geared towards things you find
> in introductory mechanics in physics and dynamics courses. It is geared
> toward dynamics of multibodies, 2D and 3D. Most schools teach this at the
> graduate level or some advanced upper level courses in engineering and
> physics.
> >
> > I have another package called "resonance" that is aligned more for 2D
> dynamics and simulation. I do teach the students to derive equations of
> motion symbolically with sympy and use the resonance interface to do the
> simulation and analysis. This is here:
> https://github.com/moorepants/resonance/
> >
> > Jason
> > moorepants.info
> > +01 530-601-9791
> >
> >
> > On Tue, May 14, 2019 at 8:59 AM Jason Moore 
> wrote:
> >>
> >> Oscar,
> >>
> >> There are some rolling disc examples here:
> https://github.com/pydy/pydy/tree/master/examples Note that the PyDy
> project started as an independent thing build on top of SymPy, then the
> symbolics were merged into sympy as the mechanic module and the numerics
> are now in the standalone PyDy package.
> >>
> >> Also, I teach an entire graduate class using the module that include
> 20+ lecture videos and accompanying notebooks:
> https://moorepants.github.io/mae223/
> >>
> >> There are also several scipy/pycon tutorials on the package:
> >>
> >> http://www.moorepants.info/portfolio/pydy.html
> >>
> >> The module may be complicated, but that may just reflect that 3D
> multibody rigid body mechanics is complicated. We've worked on some layers
> on top of the core code that have been merged or are in open PRs to help
> provide simpler interfaces that give a way to "assemble" bodies as you
> would in reality (with joints, etc) but it is still not polished for
> production. I could imagine a layer that makes it simpler to do 2D
> mechanics too, among other things.
> >>
> >> I'll be working on things this summer because I am teaching the
> aforementioned course in the fall. Feel free to open issues for discussion
> on improvements.
> >>
> >> Jason
> >> moorepants.info
> >> +01 530-601-9791
> >>
> >>
> >> On Mon, May 13, 2019 at 1:42 PM Oscar Benjamin <
> oscar.j.benja...@gmail.com> wrote:
> >>>
> >>> Hi all,
> >>>
> >>> I haven't really looked much at SymPy's mechanics module even though
> >>> mechanics is very much one of my interests and something that I like
> >>> to think I know a bit about. Today I finally took a look at it and I
> >>> found the whole API surprisingly complicated. I teach mechanics to
> >>> undergraduate students but I'm not sure if I would know how to teach
> >>> my students to use the mechanics module as it is now...
> >>>
> >>> Firstly I looked through the documentation here:
> >>> https://docs.sympy.org/latest/modules/physics/mechanics/index.html
> >>> Is there any other guide/documentation that explains the general ideas
> >>> more simply with examples?
> >>>
> >>> Suppose that I want to think about a simple 2D problem with a disc
> >>> rolling down a surface inclined at angle beta with (Coulomb) friction
> >>> coefficient mu. I want to know when/whether the disc will stick or
> >>> slip and get the equations of motion for each case. How would I go
> >>> about doing that using the mechanics module?
> >>>
> >>> --
> >>> Oscar
> >>>
> >>> --
> >>> You received this message because you are subscribed to the Google
> Groups "sympy" group.
> >>> To unsubscribe from this group and stop receiving emails from it, send
> an email to sympy+unsubscr...@googlegroups.com.
> >>> To post to this group, send email to sympy@googlegroups.com.
> >>> Visit this group at https://groups.google.com/group/sympy.
> >>> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sympy/CAHVvXxQXtAd_HGwTqaKrpDqQC_mNcyZAFgPrVe8Sq_hPwT6H0w%40mail.gmail.com
> .
> >>> For more options, visit https://groups.google.com/d/optout.
> >
> > --
> > You received 

Re: [sympy] Using the mechanics API

[Oscar Benjamin]

Thanks Jason. Those links helped.

I guess if the module is not intended for simpler problems then that
makes sense. I would say though that the documentation could benefit
from more of a tutorial somewhere.

I'll try to use it for a real problem at some point and then see what I think...

--
Oscar

On Tue, 14 May 2019 at 18:32, Jason Moore  wrote:
>
> Oscar,
>
> Also a specific answer to:
>
> > Suppose that I want to think about a simple 2D problem with a disc
> rolling down a surface inclined at angle beta with (Coulomb) friction
> coefficient mu. I want to know when/whether the disc will stick or
> slip and get the equations of motion for each case. How would I go
> about doing that using the mechanics module?
>
> This is way too simple of a problem to really use the mechanics module for. 
> If I were teaching this I would just use the base sympy features to do the 
> math. The mechanics module is not really geared towards things you find in 
> introductory mechanics in physics and dynamics courses. It is geared toward 
> dynamics of multibodies, 2D and 3D. Most schools teach this at the graduate 
> level or some advanced upper level courses in engineering and physics.
>
> I have another package called "resonance" that is aligned more for 2D 
> dynamics and simulation. I do teach the students to derive equations of 
> motion symbolically with sympy and use the resonance interface to do the 
> simulation and analysis. This is here: 
> https://github.com/moorepants/resonance/
>
> Jason
> moorepants.info
> +01 530-601-9791
>
>
> On Tue, May 14, 2019 at 8:59 AM Jason Moore  wrote:
>>
>> Oscar,
>>
>> There are some rolling disc examples here: 
>> https://github.com/pydy/pydy/tree/master/examples Note that the PyDy project 
>> started as an independent thing build on top of SymPy, then the symbolics 
>> were merged into sympy as the mechanic module and the numerics are now in 
>> the standalone PyDy package.
>>
>> Also, I teach an entire graduate class using the module that include 20+ 
>> lecture videos and accompanying notebooks: 
>> https://moorepants.github.io/mae223/
>>
>> There are also several scipy/pycon tutorials on the package:
>>
>> http://www.moorepants.info/portfolio/pydy.html
>>
>> The module may be complicated, but that may just reflect that 3D multibody 
>> rigid body mechanics is complicated. We've worked on some layers on top of 
>> the core code that have been merged or are in open PRs to help provide 
>> simpler interfaces that give a way to "assemble" bodies as you would in 
>> reality (with joints, etc) but it is still not polished for production. I 
>> could imagine a layer that makes it simpler to do 2D mechanics too, among 
>> other things.
>>
>> I'll be working on things this summer because I am teaching the 
>> aforementioned course in the fall. Feel free to open issues for discussion 
>> on improvements.
>>
>> Jason
>> moorepants.info
>> +01 530-601-9791
>>
>>
>> On Mon, May 13, 2019 at 1:42 PM Oscar Benjamin  
>> wrote:
>>>
>>> Hi all,
>>>
>>> I haven't really looked much at SymPy's mechanics module even though
>>> mechanics is very much one of my interests and something that I like
>>> to think I know a bit about. Today I finally took a look at it and I
>>> found the whole API surprisingly complicated. I teach mechanics to
>>> undergraduate students but I'm not sure if I would know how to teach
>>> my students to use the mechanics module as it is now...
>>>
>>> Firstly I looked through the documentation here:
>>> https://docs.sympy.org/latest/modules/physics/mechanics/index.html
>>> Is there any other guide/documentation that explains the general ideas
>>> more simply with examples?
>>>
>>> Suppose that I want to think about a simple 2D problem with a disc
>>> rolling down a surface inclined at angle beta with (Coulomb) friction
>>> coefficient mu. I want to know when/whether the disc will stick or
>>> slip and get the equations of motion for each case. How would I go
>>> about doing that using the mechanics module?
>>>
>>> --
>>> Oscar
>>>
>>> --
>>> You received this message because you are subscribed to the Google Groups 
>>> "sympy" group.
>>> To unsubscribe from this group and stop receiving emails from it, send an 
>>> email to sympy+unsubscr...@googlegroups.com.
>>> To post to this group, send email to sympy@googlegroups.com.
>>> Visit this group at https://groups.google.com/group/sympy.
>>> To view this discussion on the web visit 
>>> https://groups.google.com/d/msgid/sympy/CAHVvXxQXtAd_HGwTqaKrpDqQC_mNcyZAFgPrVe8Sq_hPwT6H0w%40mail.gmail.com.
>>> For more options, visit https://groups.google.com/d/optout.
>
> --
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> To view this 

[sympy] integral transform

[Chris Smith]

There is a question here 

 
about integrating `cos(x)**2` wrt `sin(x)` -- which is something that is no 
longer permitted in current versions of SymPy and this is not a permitted 
transform since solution of `u - sin(x)` does not yield a unique solution. 
Is this something that SymPy should be handling?

/c

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Re: [sympy] Using the mechanics API

[Jason Moore]

Oscar,

Also a specific answer to:

> Suppose that I want to think about a simple 2D problem with a disc
rolling down a surface inclined at angle beta with (Coulomb) friction
coefficient mu. I want to know when/whether the disc will stick or
slip and get the equations of motion for each case. How would I go
about doing that using the mechanics module?

This is way too simple of a problem to really use the mechanics module for.
If I were teaching this I would just use the base sympy features to do the
math. The mechanics module is not really geared towards things you find in
introductory mechanics in physics and dynamics courses. It is geared toward
dynamics of multibodies, 2D and 3D. Most schools teach this at the graduate
level or some advanced upper level courses in engineering and physics.

I have another package called "resonance" that is aligned more for 2D
dynamics and simulation. I do teach the students to derive equations of
motion symbolically with sympy and use the resonance interface to do the
simulation and analysis. This is here:
https://github.com/moorepants/resonance/

Jason
moorepants.info
+01 530-601-9791


On Tue, May 14, 2019 at 8:59 AM Jason Moore  wrote:

> Oscar,
>
> There are some rolling disc examples here:
> https://github.com/pydy/pydy/tree/master/examples Note that the PyDy
> project started as an independent thing build on top of SymPy, then the
> symbolics were merged into sympy as the mechanic module and the numerics
> are now in the standalone PyDy package.
>
> Also, I teach an entire graduate class using the module that include 20+
> lecture videos and accompanying notebooks:
> https://moorepants.github.io/mae223/
>
> There are also several scipy/pycon tutorials on the package:
>
> http://www.moorepants.info/portfolio/pydy.html
>
> The module may be complicated, but that may just reflect that 3D multibody
> rigid body mechanics is complicated. We've worked on some layers on top of
> the core code that have been merged or are in open PRs to help provide
> simpler interfaces that give a way to "assemble" bodies as you would in
> reality (with joints, etc) but it is still not polished for production. I
> could imagine a layer that makes it simpler to do 2D mechanics too, among
> other things.
>
> I'll be working on things this summer because I am teaching the
> aforementioned course in the fall. Feel free to open issues for discussion
> on improvements.
>
> Jason
> moorepants.info
> +01 530-601-9791
>
>
> On Mon, May 13, 2019 at 1:42 PM Oscar Benjamin 
> wrote:
>
>> Hi all,
>>
>> I haven't really looked much at SymPy's mechanics module even though
>> mechanics is very much one of my interests and something that I like
>> to think I know a bit about. Today I finally took a look at it and I
>> found the whole API surprisingly complicated. I teach mechanics to
>> undergraduate students but I'm not sure if I would know how to teach
>> my students to use the mechanics module as it is now...
>>
>> Firstly I looked through the documentation here:
>> https://docs.sympy.org/latest/modules/physics/mechanics/index.html
>> Is there any other guide/documentation that explains the general ideas
>> more simply with examples?
>>
>> Suppose that I want to think about a simple 2D problem with a disc
>> rolling down a surface inclined at angle beta with (Coulomb) friction
>> coefficient mu. I want to know when/whether the disc will stick or
>> slip and get the equations of motion for each case. How would I go
>> about doing that using the mechanics module?
>>
>> --
>> Oscar
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "sympy" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to sympy+unsubscr...@googlegroups.com.
>> To post to this group, send email to sympy@googlegroups.com.
>> Visit this group at https://groups.google.com/group/sympy.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/sympy/CAHVvXxQXtAd_HGwTqaKrpDqQC_mNcyZAFgPrVe8Sq_hPwT6H0w%40mail.gmail.com
>> .
>> For more options, visit https://groups.google.com/d/optout.
>>
>

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For more options, visit https://groups.google.com/d/optout.

Re: [sympy] Using the mechanics API

[Jason Moore]

Oscar,

There are some rolling disc examples here:
https://github.com/pydy/pydy/tree/master/examples Note that the PyDy
project started as an independent thing build on top of SymPy, then the
symbolics were merged into sympy as the mechanic module and the numerics
are now in the standalone PyDy package.

Also, I teach an entire graduate class using the module that include 20+
lecture videos and accompanying notebooks:
https://moorepants.github.io/mae223/

There are also several scipy/pycon tutorials on the package:

http://www.moorepants.info/portfolio/pydy.html

The module may be complicated, but that may just reflect that 3D multibody
rigid body mechanics is complicated. We've worked on some layers on top of
the core code that have been merged or are in open PRs to help provide
simpler interfaces that give a way to "assemble" bodies as you would in
reality (with joints, etc) but it is still not polished for production. I
could imagine a layer that makes it simpler to do 2D mechanics too, among
other things.

I'll be working on things this summer because I am teaching the
aforementioned course in the fall. Feel free to open issues for discussion
on improvements.

Jason
moorepants.info
+01 530-601-9791


On Mon, May 13, 2019 at 1:42 PM Oscar Benjamin 
wrote:

> Hi all,
>
> I haven't really looked much at SymPy's mechanics module even though
> mechanics is very much one of my interests and something that I like
> to think I know a bit about. Today I finally took a look at it and I
> found the whole API surprisingly complicated. I teach mechanics to
> undergraduate students but I'm not sure if I would know how to teach
> my students to use the mechanics module as it is now...
>
> Firstly I looked through the documentation here:
> https://docs.sympy.org/latest/modules/physics/mechanics/index.html
> Is there any other guide/documentation that explains the general ideas
> more simply with examples?
>
> Suppose that I want to think about a simple 2D problem with a disc
> rolling down a surface inclined at angle beta with (Coulomb) friction
> coefficient mu. I want to know when/whether the disc will stick or
> slip and get the equations of motion for each case. How would I go
> about doing that using the mechanics module?
>
> --
> Oscar
>
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Re: [sympy] Gsoc Project idea " Efficient Equation ofMotionGenerationwith Python" discussion.

[Oscar Benjamin]

On Thu, 14 Mar 2019 at 21:19, Aaron Meurer  wrote:
>
> I agree. The biggest challenge with symbolic matrices is expression
> blow up. In some cases it is unavoidable, for instance, symbolic
> eigenvalues/eigenvectors use the symbolic solutions to polynomials,
> which are complicated in the general case for n > 2.
>
> One thing I meant by "overhead" is that if the type of a matrix's
> entries is known to all be rational numbers, for instance, we can
> operate directly on those numbers, ideally using fast number types
> like gmpy.mpq. If they are all rational functions, we can use
> polynomial algorithms that operate on rational functions. These always
> keep rational functions in canonical form, and the zero equivalence
> testing becomes literally "expr == 0" (no simplification required).
> These can be more efficient than general symbolic manipulation.
>
> This is how the polys module is structured. See
> https://docs.sympy.org/latest/modules/polys/internals.html. It would
> be nice to have a similar structure in the matrices, where a matrix
> can have a ground domain (or type) associated with its underlying
> data.

There is an example of this here:
https://github.com/sympy/sympy/issues/16823

The matrix is all numbers of the form q1+I*q2 for rational q1 and q2
and the expressions blow up leading to terrible asymptotic
performance. It could probably be made a lot faster with judicious use
of expand but actually having a fast only complex number matrix
routine would speed that up massively.

--
Oscar

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