RE: [PEAR-DEV] New package proposal: Math_Calculus

Jesus, The site www.phpmath.com is still a BETA release, so don't expect to find there too much stuff at the moment. I do agree that PEAR coding standards, as well as phpDocumentor compatible inline documentation should be used. However at this point it's difficult to enforce this, because other admins are not exactly concerned with the format. The reason I got very interested in this particular project is because one of the admins had already published 2 articles on IBM developerworks about the Regression classes, present in the toolkit. I thought that this would be a great incentive for PHP developers to get involved. Here are the articles: http://www-106.ibm.com/developerworks/web/library/wa-linphp2/ http://www-106.ibm.com/developerworks/web/library/wa-linphp/ Regards, __________________________________________ Lukasz Karapuda [ lkarap00@mercyhurst.edu ] Mercyhurst Web Developer Y! lukaszkarapuda -----Original Message----- From: Jesus M. Castagnetto [mailto:jcastagnetto@yahoo.com] Sent: Monday, May 19, 2003 6:39 PM To: Lukasz Karapuda; 'Johannes Schlueter' Cc: pear-dev@lists.php.net Subject: RE: [PEAR-DEV] New package proposal: Math_Calculus Hi Lukasz and Johannes, --- Lukasz Karapuda <luke@thenewline.com> wrote: > > Overall the idea is good. The implementation needs some work. For > example, > > a stable and reliable differentiation package could be use to solve > funding > > the roots of an equations using any of the well-known methods (e.g. > > Newton-Raphson's). > > If you are considering developing a reliable and complete > differentiation package, take a look at http://www.phpmath.com. > Sounds interesting. A more encompasing project than the 'Numeric PHP' (one that I started eons ago, and now have terminated). Most of the code from that is in PEAR now (see the Math_* packages). > It's a > major effort to create a complete mathematical toolkit for PHP (language > based). Went to the site, found not much information. In particular I was expecting to see some downloadable code. I found the autocorrelation, distribution, and linear regression stuff code (some of which can be factored out to other packages, eg. Math_Stats in PEAR). > I am one of the administrators, and currently we are looking at > as many contributors as possible. Perhaps you could join our mailing > list. We currently have implemented Simple Linear Regression, Matrix > Operations and Linear Algebra. I did not see any matrix operations code (see PEAR::Math_Matrix). Also, it would be a good idea to use the PEAR Code Standards, for both the actual PHP code and the code documentation. Also, you might consider creating a package.xml so the classes can be installed using the PEAR installer. Finally, why not consider to create a series of Math_* classes that can be included/integrated in PEAR. Having a team of maintainers that can be grouped under the phpmath.com site would be great, that way the code will be better and the errors/bugs fewer. This can be done in two ways, by adding the packages as they are approved to PEAR's CVS, or by keeping the code in a separate CVS and releasing them via PEAR, or both ;-) > > Best Regards, > > __________________________________________ > Lukasz Karapuda [ lkarap00@mercyhurst.edu ] > Mercyhurst Web Developer > Y! lukaszkarapuda > > > -----Original Message----- > From: Johannes Schlueter [mailto:phpng@schlueters.de] > Sent: Saturday, May 17, 2003 10:03 AM > To: Jesus M. Castagnetto > Cc: pear-dev@lists.php.net > Subject: Re: [PEAR-DEV] New package proposal: Math_Calculus > > On Friday 16 May 2003 23:45, you wrote: > > The class looks OK for simple functions withouth many singular points. > > As it stands now, I would not recommend its inclusion in PEAR: -1 > > Ok. > > > 1) The name of the class: Perhaps you will be better of having 2 or > more > > Math_Numerical_Differentiation, Math_Numerical_Integration, etc. Or > how > > about a Math_Numerical (or Math_NumericalMethod or > Math_NumericalSolution?) > > class that works as facade to the ones implementing the algorithms? > > Math_Numerical looks good, but then we need many method's with it, but > I'll > look how I can implement all useful Numerical Alogrithms with PHP ;-) > > > 2) The implementation of your differentiation function, if you are > handed a > > non-continuous function, then you will be in trouble using the simple > > approach, w/o previously testing for continuity in the interval where > you > > Yes, that's true. The version I posted was the work of very few hours, > just > for solving a problem I had. Therefore it worked. Then I saw there's no > such > thing for PEAR so I wrote some comments to see the reactions, imho it > don't > make sense spending hours of work if nobody wants it ;-) > > > are calculating the derivative. A look at: > > http://lib-www.lanl.gov/numerical/index.html, and in > > particular at: > > http://lib-www.lanl.gov/numerical/bookfpdf/f5-7.pdf, will > > surely help > in > > this respect. Might also need to be careful not to generate an > floating > > point overflow. > > The links look really interesting. All have a closer look over these an > improve my code. > > > 3) The implementation of the Romberg's integration method tries to > minimize > > errors by using iterations of the trapezoidal rule. But for analytical > > functions, you might be better using other approaches. > > Romberg'smethod was the one I've found most implementations for and the > one > I've understood easily ;-) > > > 4) The method that finds point of a function where the derivative is > zero > > is OK, but it is of no use if it is not coupled with one that find the > > extrema (minima and maxima). Also, if might be better named > > findZeroDerivative() instead. Of course you will need to define a > second > > derivative method for the extrema. > > Yes... > > > Overall the idea is good. The implementation needs some work. For > example, > > a stable and reliable differentiation package could be use to solve > funding > > the roots of an equations using any of the well-known methods (e.g. > > Newton-Raphson's). > > > > The URL mentioned above has a lot of great numerical recipes. And as > we > > cannot add GSL to PECL due to licensing conflicts, perhaps > implementing > > them in PHP would be nice. > > If I'm going to implement all of them I'll never be bored again. And if > I'm > still bored I can implement it using BCMath, GMP and PEAR Math_Complex. > ;-) > > johannes > ===== --- Jesus M. Castagnetto (jcastagnetto@yahoo.com) Research: http://metallo.scripps.edu/ Personal: http://www.castagnetto.org/ __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com