@Milos Bilik 

If M is the Matrix, then do the extraction as M[2.., [4,7]]. That says "rows 2 to the end, columns 4 and 7". Converting dates to floating point is probably more complicated. I'd need to see the date format to see what you mean.

Your graph is very likely a cluster graph. Look up "graph clustering" in Google. You will need to use an algorithm for identifying the clusters. I don't know if there is any algorithm for this already in GraphTheory. Once the clusters are identified, it is easier to draw a meaningful representation of  the graph. Do a Google image search on "cluster graph" to see what I mean.

@aamirkhan 

kernelopts(version);

@LaineTrance 

RationalRoots:= proc(f::And(polynom(integer), satisfies(f-> nops(indets(f,name))=1)))
uses NT= numtheory;
local x:= indets(f,name)[], p, q, r;
     r:= select(
          r-> eval(f, x= r) = 0,      
          {0, seq(seq([p/q, -p/q][], p= NT:-divisors(tcoeff(f))), q= NT:-divisors(lcoeff(f)))}
     );
     if r = {} then printf("No rational roots") end if;
     r
end proc:

I also can run your worksheet without error.

@Doug Meade Maple's dsolve does support the numerical solution of BVPs. For example,

dsolve({diff(y(x),x$2) - y(x) = sin(x), y(0)=0, y(1)=0}, numeric);

     proc(x_bvp) ... end proc

@acer wrote:

Carl, you wrote that the problem was also exhibited when the problematic subsection was not empty. When it was not empty did it have a title?

There probably was at least a moment when it had a body but no title:  When trying to delete the subsection, I probably deleted the title first and then the body. But I've also probably done that many other times without it causing a problem.

What happened to the Answers to this Question? This was important material that I need to refer back to! If you look at the number of Replies in the Active Conversations list, it says that there are 10.

@John Fredsted Thank you. It works.

@AndreMenezes 

I think that I see where you're going with this. Maple's ability to convert between formal products and formal sums is very limited. You're better off just defining the log-likelihood function straight away.

Download Likelihood.mw

@AndreMenezes There are several ways. It would be best if you told me what your goal is. The most basic way is

Pfx:= unapply(prod, x);

A problem with that is that I suspect that you want n to represent the number of elements in x, and the function above doesn't encapsulate that. This does

Pfx:= ()-> mul(fx(x), x= args);

Then you can do

Pfx(x,y,z);

or apply Pfx to any number of arguments.

@Kitonum It's not entirely clear what the OP wants, but I assumed that they wanted the new F to equal the old F, so k1 must contain C, and k2 must contain L. But perhaps you're correct that it's the linear terms of C, L, and x1 that are wanted.

@tomleslie I think that everything in the OP's code works as it did 10 years ago. These are after all documented features, and they're still documented. If the OP were trying to use undocumented features that worked 10 years ago, that would be a different matter.

@mmcdara Using savelib combines the steps of putting expressions in .m-file format and adding them to the library. I only mentioned .m files because your original goal in this thread was to read .m files. Creating an intermediate .m file and then using march is one way of adding something to a library; savelib is the other way.

I made a mistake: My original Answer won't solve the problem in your original Question because the march(list, ...) command will only list the index names that you used with the march(add, ...) command. It won't list the names of the variables themselves. Nonetheless, the variables are stored in the library by their original names. To find those original names, you should use Tom Leslie's method.

@mmcdara You wrote:

But, before your answer I thought naively that the concept of "archive" was related ONLY to mla files and the concept of "library" 

A library is stored in an .mla file. A .mla file is constructed from .m files by using march.

I naively thought that, in Maple, the term "library" had the same meaning  whereas it seems to have a broader sense and that a library may contain other things than just procedures  ... ???

Anything the can be assigned to a variable can be in a Maple library. And in Maple anything at all can be assigned to a variable.

I have to confess here that I am probably confused between the terms archive and library ?

AFAIK, they mean exactly the same thing.

An other source of mistake is my knowledge of Matlab, where .m files generally contain structures data, not code.

In Maple, everything is a first-class citizen (see linked Wikipedia article for definition). Thus Maple code can be treated as data.