Why do you think that your procedure is thread-safe, given that it calls signum?

I don't see signum listed on the Help page for Topic threadsafe.

I don't know whether that is part cause of your problem.

It does not make sense to say that you cannot upload a Maple 11 worksheet because "Too complex to insert the Maple 11 version because I have  a complicated function  and further on".

The integral you claimed to work in Maple 11 is short. It either works, by itself and simple, or it doesn't.

@Preben Alsholm I get the following:

restart;

kernelopts(version);

    Maple 11.02, X86 64 LINUX, Nov 9 2007 Build ID 330022

with(IntegrationTools):
with(DEtools):

fx:=exp(-sqrt(x^2 + c)):

integral:=int(fx,x) assuming positive;

      int(exp(-(x^2+c)^(1/2)),x)

value(integral);

      int(exp(-(x^2+c)^(1/2)),x)

int(fx,x=xl..xu,method = _DEFAULT) assuming (x^2+c)>0,x>0,c>0;

              2     1/2
  int(exp(-(x  + c)   ), x = xl .. xu, method = _DEFAULT)

int(fx,x=xl..xu) assuming (x^2+c)>0,x>0,c>0;

   int(exp(-(x^2+c)^(1/2)),x = xl .. xu)

It is poor etiquette and unhelpful to show only an image, instead of actual code to reproduce.

You could lprint the expression, and show us that as plaintext, or you could upload and attach a worksheet using the green up-arrow in the Mapleprimes editor.

Do you work with interface(typesetting) as extended, or standard? It can make a difference, for some workarounds.

@weidade37211 I've added a few faster approaches to my Question, now edited.

One key problem in your original was coding it so as to perform the symbolic integration  int(f(x),x=0..y)  where y is a nonnumeric symbolic name. Your 2D Input of the integral is pretty-printed in black in your original, denoting the active int command.

Using a restricted range can also help the numeric root-finder (ie. fsolve).

@nmacsai I also added an alternative workaround, using a wrapping call to plots:-display.

The approach of altering the Histogram procedure is easier only if you put the preamble code in an initialization file (which would be done just once). After that the Histogram command handles your example directly.

But if you don't mind the little extra bit of typing then the plots:-display approach is also an easy way to handle your example.

@mmcdara Your comment doesn't pertain to the OP's example. And so I removed the additional, concocted example to which you objected -- which was only a sidebar here and didn't demonstrate the OP's problem.

You might discuss the new format=stacked functionality elsewhere. That's not the main subject of this Question thread.

@Guimzo Have you considered describing exactly what you want?

@David Sycamore 

Here is a worksheet. Does it run ok for you (without your making any edits to it)?

If not then you should tell us what version of Maple you are using. You should also upload and attach you'r problematic worksheet using the green up-arrow in the Mapleprimes editor.

So far you've only told us that you cannot get what you want, without actually providing us with exactly whatever you've been trying.

Download ptplot.mw

@Preben Alsholm I wasn't paying close attention, sorry -- it could have been as short as 10 minutes, and I doubt it took longer than 3/4 of an hour. I did it on Maple 2022.0 on Linux.

@bobtom Do you mean output like this?

[seq([seq([a[i,j],b[(9/2-j/2)*j-i+1]],
          i=5-j..1,-1)],
     j=1..4)];

   [[[a[4, 1], b[1]], [a[3, 1], b[2]], [a[2, 1], b[3]], [a[1, 1], b[4]]],

    [[a[3, 2], b[5]], [a[2, 2], b[6]], [a[1, 2], b[7]]],

    [[a[2, 3], b[8]], [a[1, 3], b[9]]], [[a[1, 4], b[10]]]]

Another way to consider that is as the following, when N=4,

[seq([seq([a[i,j],b[j*(2*N-j+1)/2-i+1]],
          i=N-j+1..1,-1)],
     j=1..N)];

@Lennaert van Veen Is there a reason to not make the (free) upgrade to the point-release 2021.2?

Does the problem persist if you close both the left panel (palettes), and the right panel (context-actions)?

Are you using Maple version 2021.0 or the (free upgrades to) versions 2021.1, or 2021.2?

It's good that the errant setting of that environment variable has been identified.

It might even be appropriate if the shell script that launches Maple were itself to set,
    export MKL_INTERFACE_LAYER=LP64
or similar. I'm not sure. I will submit a query. (I don't recommend it, as yet.)

But it's still a mystery why the error message you received indicates the presence of that shared library in your Maple installation's subdirectory. You showed the error message as,

   INTEL MKL ERROR: /home/jet08013/maple2022/bin.X86_64_LINUX/libmkl_gf_lp64.so: undefined symbol: mkl_blas_cdgmm_batch_strided.

But if that shared library isn't actually present in that directory then the message could be expected as,

   INTEL MKL ERROR: /home/jet08013/maple2022/bin.X86_64_LINUX/libmkl_gf_lp64.so: cannot open shared object file: No such file or directory.

Is that shared object library actually present in your Maple's bin.X86_64_LINUX subdirectory? If so, then I wonder how it got there. (I don't think that any of the new Maple 2022 python/jupyter setup adds that on purpose.)