Git and Github weren’t as intimidating as I expected. I have a repo here with the “steffen” branch including my changes:
https://github.com/jfcaron3/gsl-steffen-devel The Savannah git repo didn’t include a configure script, and I got my modified GSL+Steffen code to compile by directly modifying interpolation/Makefile AFTER running ./configure, so I’m not sure how to compile the files cloned from my github repo. At least it’s easier to see the changes now. Jean-François On Mar 25, 2014, at 14:56 , Jean-François Caron <[email protected]> wrote: > I’ve improved my initial code greatly. You can find it here: > > http://bazaar.launchpad.net/~jfcaron/+junk/my_steffen/files > > You can compile it into GSL by adding in the interpolation/Makefile > references to “steffen.c”, “steffen.lo”, and “steffen.Plo” exactly where > there are currently references to “akima.*”. > > I’ve tried adding an “integ” method, but I’m afraid I don’t even understand > the workings of the integ methods for the existing interpolation types. I > couldn’t just copy from the akima.c integ method because they use a build-in > spline calculation function (which I also don’t understand). Reading > uncommented C code is pretty hard. My test program shows that the > integration method isn’t obviously broken, but it fails the tests I wrote in > interpolation/test.c The actual interpolation and derivatives seem to work > and pass the tests. > > I’ve not used github before, so I guess my next move should be to learn the > basics and start using that, since otherwise describing my additions & > changes are hard to follow. In the meantime, is anyone able to explain how > the heck the “integ” methods work? > > Jean-François > > On Mar 20, 2014, at 11:30 , Patrick Alken <[email protected]> wrote: > >> Yes that green curve is rather strange and doesn't seem much better than the >> cubic spline. I like simplicity too so lets proceed with importing the >> steffen code. >> >> On 03/20/2014 12:18 PM, Jean-François Caron wrote: >>> Definitely an advantage of a) is that it is conceptually simple. b) is 44 >>> pages while a) is only 7. Even if b) is somehow mathematically superior, I >>> like the idea of understanding the tools that I am using (and being able to >>> explain it to my academic supervisor/conference attendees). >>> >>> The MESA astrophysics library (C++ unfortunately) actually includes both >>> types, and has a little graph to show differences: >>> http://mesa.sourceforge.net/interp_1D.html >>> >>> Actually their graph is confusing, blue is supposed to be a), green b), but >>> the green curve isn’t piece-wise monotonic between the data points. I’m >>> starting to think maybe Stetten and Huynh mean different things when they >>> say “monotonic”. I’ll try to read Huynh’s paper to see if they define what >>> they are trying to do. Steffen is pretty clear about his technique being a >>> for an interpolating function that is monotonic between data points - i.e. >>> the interpolating function doesn’t change sign between data points, and >>> extrema can only occur at said data points. >>> >>> Jean-François >>> >>> On Mar 20, 2014, at 11:03 , Patrick Alken <[email protected]> >>> wrote: >>> >>>> I see question 1) is answered by section 4 of Steffen's paper - the method >>>> works on all data sets, and preserves monotonicity in each interval, which >>>> is nice. They also state that method (c) has some serious drawbacks. >>>> >>>> Unfortunately paper (b) doesn't reference (a) and so its difficult to tell >>>> whether (b) offers any advantage over (a) >>>> >>>> On 03/20/2014 11:52 AM, Patrick Alken wrote: >>>>> Hi, I'm moving this discussion over to gsl-discuss which is more suited >>>>> for development issues. >>>>> >>>>> I have 2 naive questions which you may be able to answer since you've >>>>> been working on this code. >>>>> >>>>> 1) If the Steffen algorithm is applied to non-monotonic data, will it >>>>> still provide a solution or does the method encounter an error? >>>>> >>>>> 2) Earlier on the GSL list it was mentioned that there are 3 different >>>>> methods for interpolating monotonic data: >>>>> >>>>> (a) M.Steffen, "A simple method for monotonic interpolation in one >>>>> dimension", Astron. Astrophys. 239, 443-450 (1990). >>>>> >>>>> (b) H.T.Huynh, "Accurate Monotone Cubic Interpolation", SIAM J. Numer. >>>>> Anal. 30, 57-100 (1993). >>>>> >>>>> (c) Fritsch, F. N.; Carlson, R. E., "Monotone Piecewise Cubic >>>>> Interpolation", SIAM J. Numer. Anal. 17 (2), 238–246 (1980). >>>>> >>>>> I haven't looked at (c) but it seems that (a) and (b) both use piecewise >>>>> cubic polynomials and preserve monotonicity. Do you happen to know if >>>>> one method is superior to the other? If one method is significantly >>>>> better than the other two it would make more sense to include that one >>>>> in GSL. >>>>> >>>>> Patrick >>>>> >>>>> On 03/20/2014 11:37 AM, Jean-François Caron wrote: >>>>>> Yes, I didn’t bother doing the integration function at the time because >>>>>> I was having trouble just compiling. I will add the integration >>>>>> function, and re-write the eval and deriv/deriv2 functions to use >>>>>> Horner’s scheme for the polynomials. I can generate some comparison >>>>>> graphs using fake data like in Steffen’s paper, that sounds easy enough. >>>>>> >>>>>> I’ll look at the interpolation/test.c file and see if I can come up with >>>>>> similar tests. >>>>>> >>>>>> Thanks for offering to help with the integration into GSL itself. I >>>>>> don’t know a lot of the procedures (or even politics sometimes!) >>>>>> involved. >>>>>> >>>>>> Jean-François >>>>>> >>>>>> On Mar 20, 2014, at 10:22 , Patrick Alken <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> I did notice you talking about 1.6 in your earlier messages, but >>>>>>> assumed it was a typo and you meant 1.16, oops. >>>>>>> >>>>>>> On 03/20/2014 11:11 AM, Jean-François Caron wrote: >>>>>>>> My original problem was that I wanted to add an interpolation type to >>>>>>>> GSL. Specifically I want monotonic cubic-splines following the >>>>>>>> description in Steffen (1990): >>>>>>>> http://adsabs.harvard.edu/full/1990A%26A...239..443S >>>>>>> I took a quick look at your code earlier and it looks pretty nice. I >>>>>>> noticed you commented out the _integ function - is this something you >>>>>>> could add to make it feature complete with the other interpolation >>>>>>> types? >>>>>>> >>>>>>> It is important to add automated tests for this. Can you look at >>>>>>> interpolation/test.c and design similar tests for your new method? Also >>>>>>> I think it would be nice to add a figure to the manual illustrating the >>>>>>> differences between cubic, akima, and your new steffen method (similar >>>>>>> to the figures in the Steffen paper). This would help users a lot when >>>>>>> trying to decide what method to use. Do you happen to have a dataset >>>>>>> which shows a nice contrast like Figs 1, 3 and 8 from that paper? >>>>>>> >>>>>>> When everything is ready I would be happy to add it to GSL, as we are >>>>>>> already planning to update the interpolation module for the next >>>>>>> release. When I find some time I want to import the 2D interpolation >>>>>>> extension discussed previously, and also add Hermite interpolation. >>>>>>> >>>>>>> It would be easiest for us if you could clone the GSL git repository >>>>>>> and make your changes there. You could make a new branch called >>>>>>> 'steffen' or something and publish it to github, or just send a patch >>>>>>> file to me, whichever is easiest. >>>>>>> >>>>>>> Patrick >>>>>>> >>>>>>> On Mar 19, 2014, at 18:40 , Dave Allured - NOAA Affiliate >>>>>>> <[email protected]> wrote: >>>>>>>>> More data. I tried the same plain build recipe, GSL 1.16 on our test >>>>>>>>> machine which is at Mac OS 10.9.3. Got another perfect build, no make >>>>>>>>> check errors, no PPC-related issues. Outputs on request, please be >>>>>>>>> specific. >>>>>>>>> >>>>>>>>> CC=clang >>>>>>>>> CFLAGS=-g >>>>>>>>> ./configure --prefix /Users/dallured/Disk/3rd/gsl/1.16.os10.9 >>>>>>>>> >>>>>>>>> mac27:~/Disk/3rd/gsl/1.16.os10.9 57> sw_vers >>>>>>>>> ProductName: Mac OS X >>>>>>>>> ProductVersion: 10.9.3 >>>>>>>>> BuildVersion: 13D17 >>>>>>>>> >>>>>>>>> mac27:~/Disk/3rd/gsl/1.16.os10.9/src 36> \ >>>>>>>>> ? grep -i '# [a-z]' ../logfiles/make-check.0319a.log | sort | uniq -c >>>>>>>>> 45 # ERROR: 0 >>>>>>>>> 45 # FAIL: 0 >>>>>>>>> 42 # PASS: 1 >>>>>>>>> 3 # PASS: 2 >>>>>>>>> 45 # SKIP: 0 >>>>>>>>> 42 # TOTAL: 1 >>>>>>>>> 3 # TOTAL: 2 >>>>>>>>> 45 # XFAIL: 0 >>>>>>>>> 45 # XPASS: 0 >>>>>>>>> >>>>>>>>> mac27:~/Disk/3rd/gsl/1.16.os10.9 62> \ >>>>>>>>> ? grep -c -i ppc logfiles/*319a*log >>>>>>>>> logfiles/configure.0319a.os10.9.log:0 >>>>>>>>> logfiles/install.0319a.log:0 >>>>>>>>> logfiles/make-check.0319a.log:0 >>>>>>>>> logfiles/make.0319a.log:0 >>>>>>>>> >>>>>>>>> mac27:~/Disk/3rd/gsl/1.16.os10.9 65> \ >>>>>>>>> ? grep -i ppc src/config.h src/config.log src/config.status >>>>>>>>> src/config.h:/* #undef HAVE_GNUPPC_IEEE_INTERFACE */ >>>>>>>>> src/config.log:HAVE_GNUPPC_IEEE_INTERFACE='' >>>>>>>>> src/config.status:S["HAVE_GNUPPC_IEEE_INTERFACE"]="" >>>>>>>>> >>>>>>>>> --Dave >>>>>>>>> >>>>>>>>> On Wed, Mar 19, 2014 at 5:27 PM, Jean-Francois Caron >>>>>>>>> <[email protected]> >>>>>>>>> wrote: >>>>>>>>>> Dave is correct, I am using an "i686" 64-bit x86 mac. For some >>>>>>>>>> reason >>>>>>>>>> it is still looking for the PPC mac header file. The ./configure >>>>>>>>>> stage correctly identifies my system, so it's a bit strange. Also >>>>>>>>>> GSL >>>>>>>>>> installs without errors when I do it from MacPorts, and MacPorts >>>>>>>>>> doesn't seem to do anything other than ./configure && make, from my >>>>>>>>>> reading of the portfile. >>>>>>>>>> >>>>>>>>>> When I get back to my Mac, I will look at the NOTES file to see if >>>>>>>>>> anything needs to be done for 10.9. >>>>>>>>>> >>>>>>>>>> Jean-François >> >
