Hi, On 1 November 2011 09:22, Aaron Meurer <[email protected]> wrote:
> On Mon, Oct 31, 2011 at 6:37 PM, David Joyner <[email protected]> wrote: > > On Mon, Oct 31, 2011 at 7:31 PM, Aaron Meurer <[email protected]> > wrote: > >> Comments: > >> > >> - "as its beautiful logo" should this be "as is its beautiful logo"? > > > > fixed > > > >> > >> - "However, the most active are..." Maybe rather say "However, the > >> most active as of October 2011 are..." to make it clear that this is a > >> snapshot into this particular point in time. For example, over the > >> summer a different set of developers were most active (i.e., these > >> people plus the GSoC students). > > > > fixed > > > >> > >> - "For example, the following simple Python commands were run from the > >> SymPy command line." I would reword this sentence. It sounds like > >> SymPy has it's own interpreter, and I think it especially would to a > >> user of any other computer algebra system. I'm not sure what the best > >> wording is, but make it clear that SymPy just runs inside a normal > >> Python interpreter, such as the one that comes with Python or IPython. > >> Maybe it would be best to just include a short paragraph about the > >> isympy script, which just paraphrases the docstring from that file. > > > > revised, as suggested > > > >> > >> "Surprisingly, it seems Maxima cannot do this at the present time." If > >> I remember correctly, Maxima took the lazy route and only implemented > >> second order differential equations (or maybe they can also do higher > >> order but only if they are homogeneous, I can't remember). The > >> general non-homogeneous case requires either undetermined coefficients > >> (if the non-homogeneous term has the correct form), or, in the general > >> case, the nth order version of variation of parameters, which is not > >> too difficult to implement if you have strong integration routines and > >> knowledge of linear algebra (Cramer's rule), but it seems is so rarely > >> actually taught that I only found two resources anywhere on the > >> internet that dealt with it in the nth case out of the thousands that > >> dealt with the 2nd order case, and neither was very good. I discussed > >> this on my blog back when I implemented it > >> ( > http://asmeurersympy.wordpress.com/2009/08/01/variation-of-parameters-and-more/ > ). > >> In fact, at the time, I couldn't find another open source system that > >> implemented this, though I would definitely try to verify this fact > >> before putting it in the paper. > >> > > > > I made revisions but I think Axiom has more functionality that Maxima > > in this area: > > > http://www.axiom-developer.org/axiom-website/hyperdoc/equdifferentiallinear.xhtml > > > > Ah, that's not surprising. Axiom probably implements something like > http://www-sop.inria.fr/cafe/Manuel.Bronstein/sumit/bernina_demo.html. > There are algorithms for solving certain classes of differential equations in full generality (e.g. linear with polynomial coefficients). See http://reference.wolfram.com/mathematica/tutorial/DSolveReferences.html and search for Bronstain and Abramov. Actually, one of those algorithms I implemented during my summer of code for the discrete case (recurrence solving), but it can be generalized to the continuous case. I'm not sure if they are implemented in Axiom, but most certainly they are implemented in various libraries (in Aldor) written by Bronstein. > > Aaron Meurer > > > > >> "On the > >> other hand, perhaps it is not surprising that SymPy is relatively > strong in > >> the area of differential equations since many or the developers come from > >> physics and computational mathematics communities." Actually it's > >> mainly because of my GSoC project :) > > > > > > Good point. I changed that. > > > > New version posted to the usual place:-) > > > > Thanks Aaron! > > > >> > >> Aaron Meurer > >> > >> On Mon, Oct 31, 2011 at 4:33 PM, David Joyner <[email protected]> > wrote: > >>> On Sun, Oct 30, 2011 at 12:48 PM, Vladimir Perić < > [email protected]> wrote: > >>> > >>> ... > >>> > >>>> > >>>> I also think the "Capabilities" section is a bit.. short. You took it > >>>> from the website, I assume? That homepage hasn't been updated in a > >>>> long time (and writing that list is even one task for Google Code-In). > >>>> At the very least, I think you should give more mention to the physics > >>>> and quantum modules, which is a real advantage SymPy has over other > >>>> CAS systems. > >>> > >>> > >>> After a few emails from Brian Granger (thanks Brian!) I have > >>> created a new subsection on quanum physics. It is very sketchy > >>> but hopefully has enough for interested readers to pursue > >>> further leads. > >>> > >>> Latest version is at > >>> http://boxen.math.washington.edu/home/wdj/sigsam/sympy/oscas-sympy.pdf > >>> (and sources are in that directory too). > >>> > >>> BTW, if anyone wants to post this to github, that is fine with me. > >>> However, I know > >>> zip about git:-) > >>> > >>> > >>> Thanks to all of you for your great help! > >>> > >>>> > >>> > >>> ... > >>> > >>>> -- > >>>> Vladimir Perić > >>>> > >>>> -- > >>>> You received this message because you are subscribed to the Google > Groups "sympy" group. > >>>> To post to this group, send email to [email protected]. > >>>> To unsubscribe from this group, send email to > [email protected]. > >>>> For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > >>>> > >>>> > >>> > >>> -- > >>> You received this message because you are subscribed to the Google > Groups "sympy" group. > >>> To post to this group, send email to [email protected]. > >>> To unsubscribe from this group, send email to > [email protected]. > >>> For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > >>> > >>> > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups "sympy" group. > >> To post to this group, send email to [email protected]. > >> To unsubscribe from this group, send email to > [email protected]. > >> For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > >> > >> > > > > -- > > You received this message because you are subscribed to the Google > Groups "sympy" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > [email protected]. > > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > > > > > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/sympy?hl=en. > > Mateusz -- You received this message because you are subscribed to the Google Groups "sympy" group. 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