Mac Dude

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7 years, 267 days

MaplePrimes Activity


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@DSkoog Ok, so I was able to create a Lattice.maple file by omitting the Users Guide and removing the continuation characters from the PackageTools:-Create command. Putting that into a directory known in libname indeed allows with() to work. Good. (I realize now that I did not check the help files...).

From what you wrote it appears that PackageTools:-Install creates a new, hard-wired directory structure in my home directory (maple/toolbox/...). What if I want this to be somewhere else? What is this guy "%USERFOLDER%"? Can I set this to some folder I chose? I am familiar with the kernelopts() directories and with currentdir() and libname; but this is a new one for me.

Thanks,

M.D.

@dharr Hmm... thanks much for finding this out.

The page breaks I have in the file are there for reason of structuring the document esp. when printed to a pdf and looked at in this way, and I am not really interested in removing them. I don't know what a "child page break" is supposed to be; but this will prevent me from creating a workbook of Lattice. It is actually a real issue: Maple has the unique ability to allow typesetting text; adding things like page breaks and line breaks etc. are a fairly fundamental part of it. For our accelerator physics course I practically wrote a book in Maple. If workbooks do not support this it mars the concept.

And I cannot even fathom why the workbook even cares about these.

Anyway, needs to get fixed pronto. SCR incoming.

  :-(

M.D.

@nm if the fopen() call fails, Maple stops unless you catch the error using try...catch. If it does not stop, the fopen was successfull & you can rely on the filehandle being valid.

Does not seem to be that bad to me. If you want to get fancy, try...catch allows you to parse the error message & catch only specific errors, so you can take specific actions. E.g. if you try to fopen an already open file, fopen will fail as well (per the help page) and you can catch that. Although I have had trouble with this mechanism & gave up on being fancy.

High-level, but in my view not so bad. Incidentally, I do not fund the help page that bad. It explains all this pretty much.

M.D.

@MTata94 @phil2 The FAQ phil2 mentions seems to address mostly issues where the Maple GUI cannot connect to the kernel. This is not the case for you MTata94, if I understand correctly.

Independent of that, however, you should have the files mentioned in the FAQ; these are the main Maple binaries. Without them you would not have a working installation. Note that on OS X, there is a /Library, sitting in Macintosh HD (your boot disk) and a ~/Library, sitting in your home directory. The Maple frameworks will be in /Library.

What are the general settings of your Firewall?

M.D.

@John Fredsted Probably not, as when Maple hangs it will never get to the time statement.

I have used a variation on your theme, however: In a lengthy piece of code I would store the values of time()-t after each specific step in an array with the index counting up as the code goes along. When it got stuck I would break out & examine the array & see how far the code got. If it goes around the loop then you look for the value going down with increasing index; that is where the previous iteration values are still present & Maple hung.

When the code runs the overhead at least in my case was insignificant.

Another thing I would do for lengthy loops is to setup a gauge indicator that increments each iteration of the loop. This gives a nice visual clue of progress.

I do like acer's suggestion, however.

Mac Dude

 

Your post resonated with me. I occasionally teach a course in Advanced Accelerator Physics at the US Particle Accelerator School (USPAS.fnal.gov), together with a colleague from CERN, and it is done just in the same way you describe: highly intensive 1- or 2-week courses, in essence cramming a whole semester's worth of material into two weeks. Two lectures a day and exercises in the evening. Classes are relatively small and lots of hands-on and 1:1 contact.  Students (which in our case are mostly either graduate students or those working in the field e.g. as operators or engineers wanting to deepen their understanding) are highly motivated and boy, do they hold their teachers accountable (in a good way)! It is a very rewarding endeavour, even if we are pretty drained by the end.

We do use scripts; in essence we wrote a textbook in Maple, with all the calculations live, obviously. Even though I curse regularly at Mape's 2-D input & printing, it is actually a big kudos to Maple that this is practical. As part of the tuition the students get student-licenses for Maple that they can keep, which I consider an essential element of the course, and which we know to be attractive.

We are still a bit struggling with keeping the lectures as interactive as possible. We added a sidebar to the script files where students could do their own explorations but the feedback on that was mixed: there just isn't enough room on a laptop screen for doing this in a nice way. The next time we may try putting a field below certain sections in the script where students can work on a given aspect. Lenin Araujo Castillo has just posted here one of his worksheets, and I like his layout, maybe we can experiment with that.

I visited IHEP in Beijing two years ago (as visitor-scientist, not as teacher). Your experience sounds very familiar.

For me personally, Maple opened up a path to teaching that I may not have gone otherwise. Using Maple allowed us to create a better course, and feedback we have gotten recently validates this impression. We do work hard on our course, using Maple in itself certainly does not guarantee a good learning experience (as I am sure you & everyone else who uses Maple in teaching already knows).

Thanks again for your post, much appreciated.

Uli Wienands
Argonne National Laboratory.

Any chance you have a beta license that is expiring lying around, that your version of Maple picks up? I had the same thing happen when I installed Maple 2017 beta, which would get in the way before my regular Maple 2016 got a chance.

M.D.

@9009134 Ok, what is it you want? If you just want a solution to ode1; Maple will do this at least numerically; read up on dsolve(). Maybe it can even be solved analytically.

If you want to program a numeric solution (e.g. for homework) then you'd need to go back to your classroom material to figure out where to begin. I haven't programmed a d.e. solver in a long time so I m not in a position to write the solution down for you. There are many articles on the web about such mehods (look up e.g. Runge Kutta).

And Kitonum of course is correct, to define a function you need to put the arguments in (). But I think this is only a small part of your problem. I find the eval in your assignment to eq problematic. Syntactically you can make it more correct by writing f[i,j](x,y) and maybe include these in the argument list in the F1xx etc.  but I do not really understand your code. Also, while putting indicaes as arguments (to the F1xx etc) may be syntactically ok in Maple, it certainly does not smell right.

My apologies, but I would need more of an explanation what it is you are trying to do and the steps you are going to take before I can do anything for you.

M.D.

Please give an example of what you have and what you want it to look like.

M.D.

@Christiawanta Well, you use x already in your sum; and NLPSolve minimizes a function by varying its independent variables (indets in Maple lingo) so no, you don't need or want x explicitly in NLPSolve. While your data table suggest this is a kind of least-square-type minimization, it is formulated as a minimization problem for a function and does not explicitly deal with x other than in the sum of the terms. Since the terms are all squared the sum should be positive definite (unless you have complex terms, which you should not) and should have a minimum.

Some observations: You use a both as a "function" as well as a variable storing one of your constraints. I suggest you get rid of the line a(x):=qtopi[x] as you don't need it. Just put qtopi[x] into your expression to be minimized. While you are at it, please change sum() to add(); sum() tries to evaluate a symbolic sum into a closed expression, which is not what you want here.

I would also try to get rid of the first constraint (the sum of the psi angles to be 1) by eliminating one of the angles (psi3=1-psi1+psi2). You have already more constraints than is healthy so getting rid of one can only help.

I would also try to evaluate your expression numerically for a set of parameter values that fulfills all the constraints, just to see if the answer makes any sense. If you have such a set you can even consider building up the number of variables to be included in the optimization problem, thereby finding when the algorithm gets into trouble (if it gets into trouble).

Cheers,

M.D.

@greenloafer Ahh... the plot thickens, so to speak.

It appears that the amer_approx code calls functions out of the bs program. The way to do this properly in Maple would be by wrapping up all the functions from bs (after conversion to proper Maple syntax) in a module, or even better a package (which is a module with option package specified) and export each function (which we then should call a method). So

bs:=module() option package
export N,phi,... ; # sequence of all the function names in bs
<here come all your functions, one after the other in arbitrary order, just following the template I gave earlier>
end module;

Since you are not familiar with Maple I suggest you pre-pend this whole module to your converted amer_approx code and call (execute) bs on the first line. After that you can use all the functions just like having written them without the module construct. The (better) alternative would be to save this as a .mla file and put it into a library and loading it using with(bs); but that involves some trickyness in getting Maple to do this and later find it & I do not recommend this until you have gotten your feet wet in Maple and also debugged the routines. If you expect to use these more often, however, that is what you will eventually want to do.

Just for completeness, there is a more pedestrian alternative: you can put the Maple code into a text file, save it with extension .mpl and then code

read("/path/bs.mpl");

This will read and execute the code and thereby define all the functions. Here /path/ is the directory path to the file (in Windows it would be something like C:\...\). You can still make a module and may have to execute that.

Presumably the thesis referenced in the header of amer_approx.txt has explanations how this model works and maybe even test cases.

M.D.

@greenloafer Ok, you have in your python file

def phi(z):
        return exp(-.5 * z * z) / (sqrt( 2 * pi ))

This obviously defines a function phi(z). In Maple, the general way to do the same thing would be to define a procedure like this:

phi:=proc(z)
  return exp(-.5 * z * z) / (sqrt( 2 * Pi ))
end proc;

(and before this gets side-tracked, since phi is a function the more terse way would be to write
phi:=z -> exp(-.5 * z * z) / (sqrt( 2 * Pi ));
but that would not work with a more procedural routine. proc() always works.)

You then use your function by assignment:

y:=phi(z);

I urge again to make the effort reading some of the documentation. It is worth it if you want to use Maple on a routine basis and derive the benefit.

M.D.

Edit: Pi is capitalized in Maple.

@greenloafer I don't really program in python, but this code looks straightforward to port to Maple.

def function() becomes function:=proc()...end proc;

= assignments become := in Maple

** becomes ^

pi becomes Pi

and all statements need to be terminated with ; or with : (if you want to suppress output),

and that seems mostly it, with one important caveat: Maple being a symbolic environment will keep anything that isn't assigned a number to as a symbol. This leads to the potential of accumulating huge expressions and slowing things to a crawl just because of a spelling error or a forgotten assignment. You can partially avoid this trap by wrapping your functions and/or expressions in an evalhf() statement, but that can fail in other ways. evalf() does not work, it will just evaluate what it can & leave the rest symbolic.

You may run into some names that Maple considers reserved works in which case you'll have to rename them.

M.D.

Edit: removed incorrect comment about N() being undefined. It is in fact defined at the top of the file.

Although I never use palettes, I can see this being useful for large packages with many different functions or procedures. Having the package—upon loading—create a palette as you describe thus giving access to the top-level functions of the package should be a nice facility esp. for novice users.

Thanks for sharing this,

M.D.

@akhmeteli I don't have time right now to try this myself (and the math is beyond my knowledge) but if your algorithm is a loop construct (like 2.25 in the paper) then I would, as a first step, use print() to have it put out some status info on each pass. Yes, it'll litter your worksheet but at least you can see where it slows down or hangs. Per se, >1 GB should not be a problem on a 64-bit system; maybe a problem on a 32 bit system, though (and on macOS at least I have seen the mserver process take twice as much memory than it advertises on the status like). And I have seen Maple choke on large expressions like this.

Gotta go,

 

M.D.

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