@chinthak 

Oddly enough, nearly the same commands do it in reverse. Forget about solutionlist; it's totally unnecessary. Create the tensor directly from solutions:

T:= eval(Array((1..4)$6, ()-> index(S, args)), solutions);

That's all there is to it!

I know nothing about this nightmare with the update Maple 2019.2 other than what I've read here on MaplePrimes. (Fortunately, I didn't update my own Maple.) The problem that you describe seems consistent with what I've read. And, according to what I've read, you can work around the bug by removing the restart command from your worksheet. IMO, this is the most catasthropic bug ever released into Maple. That leads me to believe that it'll be fixed soon.

@chinthak Ah, yes, I now see the ambiguous interpretations of your Question as essentially being opposites.

To answer, I need to know how the list is organized. In other words, which indices of the tensor correspond to the n^th list element? The easiest situation would be that the indices are the base-4 representation of n-1 with each digit increased by 1.

Or perhaps your list entries already contain the indices in some form?

@SaeedAF7 Thank you, and a Vote Up. It's exactly what I was looking for. 

@rameen hamood 

More hints:

4. The results of any command can be made into a set by enclosing the command in curly braces { }.

5. Any command can be made to operate elementwise, e.g. individually on the elements of a set, by appending ~ to its name, e.g. abs~.

6. The non-real roots of a real polynomial always occur as conjugate pairs. The members of such a pair have the same modulus. 

@acer Thank you for the clarification; I was suspicious of that. I should probably not try understanding unformatted 2D ASCII output on my phone. 

@acer Ouch, the syntax of that undocumented command is a nightmare. Hopefully that gets completely redone before it's ready for "prime time". Consistency demands at the very least that it be convert, not eval, and that the arguments be interchanged.

@Rouben Rostamian  Thank you, and a Vote Up; that's quite informative. I wasn't previously aware of the importance of the distinction between the magnitudes and their ratios.

@SaeedAF7 The question that I just posed to Rouben in a Reply above I also pose to you. Although I don't have MapleSim, just seeing the animation here would sate my curiosity.

@Rouben Rostamian  Just curiousity here: I know that if the cylinders were hollow (and, for simplicity, let's say uncapped), their moments of inertia would be different. How would this affect the plot? For simplicity, let's say that the cylinders are made from sheets of a dense metal of neglible thickness.

@Stretto You cannot change kernelopts(homedir). You may be confusing that with currentdir(...), which can be readily changed with 

currentdir("whatever"):

If you use colons to suppress the output of commands in the initialization file, then their output will not show in your worksheet.

@Stretto The underscore character is not an operator---it's treated like a letter of the alphabet---and it can't be overloaded. But you can define an operator &_, and you wouldn't even need to overload it because it has no predefined meaning:

`&_`:= q:

Now x &_ n returns q(x,n). Note that a space is needed after the underscore; the space before the & is optional.

@tomleslie Your solutions happens to satisfy the 0..1 constraints, but it seems like just luck that it does so.

@shkarah I watched parts of the video. Parts of it move too fast to understand, and parts of it move too slow to bear watching. Anyway, I agree that you've been led astray by it, and I don't know why it works in the video.  Is it possible to get the worksheet from the video's maker?

I concur with Acer and Christian. After the value of f(x) has been assigned, any references to f[i] are suspect and risky. Sometimes it works, but is it worth the effort to debug if it doesn't? Just use another name instead. 

I haven't investigated this case; I just formed an opinion from reading your code.

@permanoon123 Still, it's not possible to get an answer without knowing the function f.