tomleslie

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These are questions asked by tomleslie

Background

This 'quirk' of Maple behaviour cropped up when I was considering solutions for the question posted here

https://www.mapleprimes.com/questions/232433-Extract-From-Record

where the OP had "poorly structured" data which meant it was a bit "awkward" to access required fields. A number of more-or-less satisfactory solution were proposed, and the OP seems happy

 

The Issue

One possible way to solve the original problem would be to restructure the data as a DataFrame. The "natural" way to do this would be to use numeric row indexes.. Note that these row indexes are not contiguous, and are in no particular order. However using this approach means that accessing fields from the dataframe is not consistent.

Sometimes the supplied row label is interpreted as a 'label', sometimes it is interpreted as the "row number". It appears that the latter interpretation is preferentially used

I can't make up my mind whether to call this a "bug" or not, but I can see the inconsistent interpretation resulting in chaos.

Before submitting an SCR I'd like to know if anyone else sees this as a bug

Consider the code

  restart;
  prettyprint=1:
#
# data
#
  S := [`206` = Record(mu = 508.001018040,  sigma = 125.002863204708),
          `4` = Record(mu = 1008.001018040, sigma = 167.707232430134),
          `2` = Record(mu = 1208.001018040, sigma = 141.512246146314),
          `5` = Record(mu = 808.001018040,  sigma = 117.156800098735)
       ]:
#
# Construct the above as a dataframe - note row labels are numbers!
#
  DF:= DataFrame( Matrix([seq( [rhs(j):-mu, rhs(j):-sigma], j in S)]),
                  rows= [seq( parse( lhs(j) ), j in S)],
                  columns=[mu, sigma]
              );
  DF[206, mu];
  DF[2, mu];  ## Errr No!
  DF[5, sigma];
               [           mu             sigma      ]
               [                                     ]
               [206  508.001018040   125.002863204708]
               [                                     ]
         DF := [ 4   1008.001018040  167.707232430134]
               [                                     ]
               [ 2   1208.001018040  141.512246146314]
               [                                     ]
               [ 5   808.001018040   117.156800098735]

                         508.001018040

                         1008.001018040

                        117.156800098735

Note that DF[2, mu] outputs the entry from the second row - not the one from the row labelled with the number 2

I imagina a similar issue would occur with numeric column indexes, although I haven't tried this
     

 

 

There seems to be an "issue" when using a indexed name (say x[4]) as the loop index in a seq() mul() or add() command - the indexed name is assigned once the command exits!!

This never(?) happens if the loop index is not an indexed name. A bug??

See the attached which illustrates the issue for the add() command, where x[4] is assigned on exit from add(). The same thing happens if add() is replaced with seq() or mul()

  restart;

#
# x[4] should not be assigned on exit from add() !!
#
  add( u(x[4]), x[4]=1..10);
  x[4];
#
# x__4 is not assigned on exit from add()
#
  add( u(x__4), x__4=1..10);
  x__4;
#
# j is not assigned on exit from add()
#
  add( u(j), j=1..10);
  j;

u(1)+u(2)+u(3)+u(4)+u(5)+u(6)+u(7)+u(8)+u(9)+u(10)

 

10

 

u(1)+u(2)+u(3)+u(4)+u(5)+u(6)+u(7)+u(8)+u(9)+u(10)

 

x__4

 

u(1)+u(2)+u(3)+u(4)+u(5)+u(6)+u(7)+u(8)+u(9)+u(10)

 

j

(1)

 


 

Download aBug.mw

 

 

In an answer to an earlier question

https://mapleprimes.com/questions/232067-Error-Invalid-Neutral-Operator

I inadvertently used the "Insert Contents" link - AND IT WORKED

Anybody know how long this has been fixed?

Anyone have a problem with non-appearance of the animation toolbar in Maple 2021????

 

Whilst coming up with a response for the problem here

https://www.mapleprimes.com/questions/231862-Have-You-Ever-Heard-Of-Vector-Asterisks-

I found an issue with the non-appearance of the animation toolbar in Maple 2021. This is rather difficult to illustrate without the use of screenshots, for which I apologise.

Normally(?) I would just select a plot and the animation toolbar appears "as if by magic"

First screen shot is using Maple 2020, The blue highlighting rectangle around the plot was visible when I initiated the snip, but disappeared when the snipping tool activated. However this shows that the animation toolbar is available (and works)

I do exactly the same thing in  Maple 2021 and I can't make the animation toolbar appear - see below. Aagain the plot wa highlighted when I initiated the snip but the highlighting disappeared when the snipping tool activated. Now there is no sign of the animation toolbar

It is still possible to do very basic animation in Maple 2021 by clicking on the plot and using the context menu - but this is very basic

The code used in the above plots is given supplied below

  restart;
  kernelopts(version);
  plots:-display
         ( [ seq
             ( plot
               ( Vector([1, 3, 4, 6]),
                 Vector([8, 6, 2, 5]),
                 style = point,
                 symbol = j,
                 symbolsize = 40,
                 color = blue
               ),
               j in [ asterisk, box, circle, cross, diagonalcross,
                      diamond, point, solidbox, solidcircle, soliddiamond
                    ]
             )
           ],
           insequence = true
         );

Is it just me?

My OS is Windows 7 64-bit

I can't install the Physics Updates package in Maple 2020.1 and I'm looking for suggestions from anyone who has managed to do this, particularly on the above OS

Detailed timeline Nad what I have tried so far

  1. A couple of days ago I upgraded to Maple 2020.1
  2. I immediately started getting random warnings in Maple worksheets, which essentially stated that the installed Physics package (version 707) was designed for MAple 2020.0 and needed to be updated. However when I checked for \Physics updates none were available.
  3. So far, not a big problem, I figured the a Physics Update appropriate for Maple 2020.1would become available over the next few days
  4. Today I noticed that Physics Updates version 708 was available, and I made the rash(?) assumption that this would be the version I need for use with Maple 2020.1, so I tried to install it
  5. Using the icon in the top right of the the Maple worksheet in the usual way, I tried to install this update. The relevant pop-up finishes the download process, statrts the installlation process, gets about halfway through then stops along with another pop-up saying that mserver.exe has stopped working. Since the installation process was getting nowhere, I shut down Maple.
  6. Restarting Maple, and executing Physics:-Version(), I get the output `The "Physics Updates" version "708" is installed but is not active. The active version of Physics is within the library C:\\Program Files\\Maple 2020\\lib\\maple.mla, created 2020, March 5, 1:36 hours`. So maybe it did install? No, the "default location" for this package (which on my system is C:\Users\TomLeslie\maple\toolbox) contains a 'Physics Updates' folder, but the only thing in it is a 'version.txt file, which (amongst other things) contains the line cloud-version: 708.
  7. Normallly this 'Physics Updates' folder should contain a 'lib' subfolder, which in turn contains the file 'Physics Updates.maple' - but none of these exist, so I'm not convinced by the statement in (6) above that `The "Physics Updates" version "708" is installed
  8. At this stage I go into debug mode, and amognst other things, I have tried
    1. Repeat the process in (5)-(7) above - same result (including the mserver.exe crash)
    2. Delete the default installation folder C:\Users\TomLeslie\maple\toolbox\Physics Updates, and repeat the process in (5)-(7) above - same result (including the mserver.exe crash)
    3. Try 8.1 and 8.2 above running as administrator - same result
    4. Figure that maybe I have totally screwed my Maple 2020 installation, so reinstalled it, reactivated it, and updated it to 2020.1
    5. Repeated steps 8.1 to 8.3 above with exactly the same result
  9. Decide I am getting nowhere, so delete the folder C:\Users\TomLeslie\maple\toolbox\Physics Updates. The command Physics:-Version(); now returns `The "Physics Updates" package is not installed` so I assume I'm running on the Physics version which actually ships with the Maple 2020 release
  10. All suggestion for getting Physics updates running with Maple 2020.1 on 64-bit Windows 7 will be gratefully received
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