Garage door motor replacement

What do you do when your garage door is in need of urgent repair or service? Or when you think it might be in need of some attention to prevent it from having problems in the future? You call AAA Garage Door Repairs, of course. The more you know about the different kinds of automatic garage door repair, the easier it will be to determine the nature of repairs. Let’s look at the main types of garage door and explore the garage door repairs we offer throughout Brisbane, whether you’re in the centre or the suburbs.

One of the most frequently asked questions we get is, “Do you really need an automatic garage door repair company in Brisbane?” Maintenance in the form of annual servicing is crucial whether you’ve got an automatic garage door needing a remote or a manual entry system. By taking preventive action and having your garage door serviced, you’ll save money in the long run. If one part of your garage door system wears down or malfunctions, this can place undue strain on other components. Neglecting maintenance is also far more likely to create an emergency situation giving you no choice but to call in the professionals at the least convenient time.

MapleFlow is showing the exact same icon in the taskbar as Maple when both are open.  Be nice if they were slightly different.

Maple 2023: The colorbar option for contour plots does not work when used with the Explore command. See the example below.

No_colorbar_when_exploring_contour_plots.mw
 

The inverse problem of a mathematical question is often very interesting.

I'm glad to see that Maple 2023 has added several new graph operations. The GraphTheory[ConormalProduct], GraphTheory[LexicographicProduct], GraphTheory[ModularProduct] and GraphTheory[StrongProduct] commands were introduced in Maple 2023.

In fact, we often encounter their inverse problems in graph theory as well. Fortunately, most of them can find corresponding algorithms, but the implementation of these algorithms is almost nonexistent.

I once asked a question involving the inverse operation of the lexicographic product.

• https://www.mapleprimes.com/questions/235863-An-Inverse-Problem-Of-Lexicographic

Today, I will introduce the inverse operation of line graph operations. (In fact, I am trying to approach these problems with a unified perspective.)

To obtain the line graph of a graph is easy, but what about the reverse? That is to say, to test whether the graph is a line graph. Moreover, if a graph  g is the line graph of some other graph h, can we find h? (Maybe not unique. **Whitney isomorphism theorem tells us that if the line graphs of two connected graphs are isomorphic, then the underlying graphs are isomorphic, except in the case of the triangle graph K_3 and the claw K_{1,3}, which have isomorphic line graphs but are not themselves isomorphic.)

Wikipedia tells us that there are two approaches, one of which is to check if the graph contains any of the nine forbidden induced subgraphs. 

Beineke's forbidden-subgraph characterization:  A graph is a line graph if and only if it does not contain one of these nine graphs as an induced subgraph.

This approach can always be implemented, but it may not be very fast. Another approach is to use the linear time algorithms mentioned in the following article. 

• Roussopoulos, N. D. (1973), "A max {m,n} algorithm for determining the graph H from its line graph G", Information Processing Letters, 2 (4): 108–112, doi:10.1016/0020-0190(73)90029-X, MR 0424435

Or: 

•   Lehot, Philippe G. H. (1974), "An optimal algorithm to detect a line graph and output its root graph", Journal of the ACM, 21 (4): 569–575, doi:10.1145/321850.321853, MR 0347690, S2CID 15036484.

SageMath can do that: 

   root_graph()

Return the root graph corresponding to the given graph.

    is_line_graph()

Check whether a graph is a line graph.

For example, K_{2,2,2,2} is not the line graph of any graph.

K2222 = graphs.CompleteMultipartiteGraph([2, 2, 2, 2])
C=K2222.is_line_graph(certificate=True)[1]
C.show() # Containing the ninth forbidden induced subgraph.

Another Sage example for showing that the complement of the Petersen graph is the line graph of K_5.

P = graphs.PetersenGraph()
C = P.complement()
sage.graphs.line_graph.root_graph(C, verbose=False)

(Graph on 5 vertices, {0: (0, 1), 1: (2, 3), 2: (0, 4), 3: (1, 3), 4: (2, 4), 5: (3, 4), 6: (1, 4), 7: (1, 2), 8: (0, 2), 9: (0, 3)})

Following this line of thought, can Maple gradually implement the inverse operations of some standard graph operations? 

Here are some examples:

•   CartesianProduct
•   TensorProduct
•   ConormalProduct
•   LexicographicProduct
•   ModularProduct
•   StrongProduct
•   LineGraph
•  GraphPower

I did not see such a post for 2023 so I am starting one.

What is your 3 top bug fixes or improvements  you would like to see in Maple 2023? 

Here are mine

1. Fix timelimit so that it completes at or near the time requested and not hang or take 10 hrs when asked to timeout after say 30 seconds.
2. Fix the large amount of server crashes and the many random hangs when running large computation that takes long time. i.e. Make Maple more robust.
3. Allow the user to remove output from worksheet while it is still running (Evaluate->Remove output from worksheet)

Maple is a nice language and has many nice functions. But it is the usability part of Maple that leaves many bad impressions because of these things that should really have been fixed by now given how long  Maple software have been around.

Transfer functions are normally not used with units. Involving units when deriving transfer functions can help identify unit inconsistencies and reduce the likelihood of unit conversion errors.

Maple is already a great help in not having to do this manually. However, the final step of simplification still requires manual intervention, as shown in this example.

Download Collecting_and_expanding_units.mw

In an old post, vv reported a bug in simpl/max, which has been "fixed" in Maple 2018. However, it seem that such repairs are not complete enough.
For example, suppose it is required to find the (squared) distance between the origin and a point on x³ - x + y² = ⅓ which is closest to the origin. In other words, one needs to minimize x²＋y² among the points on this curve, i.e., 

extrema(x^2 + y^2, {x^3 + y^2 - x = 1/3}, {x, y}, 's'); # in exact form

Unfortunately, an identical error message appears again: 

Download tryHarder.mws

How about changing the values of parameter ?

for a from -3 by 3/27 to 3 do
    try
        extrema(x^2 + y^2, {x^3 + y^2 - x = a}, {x, y}); 
    catch:
        print(a); 
    end;
od;
                               -1
                               --
                               3 

                               -2
                               --
                               9 

                               -1
                               --
                               9 

                               1
                               -
                               9

                               2
                               -
                               9

                               1
                               -
                               3

By the way, like extrema, Student[MultivariateCalculus]:-LagrangeMultipliers also executes the Lagrange Multiplier method, but strangely, 

Student[MultivariateCalculus][LagrangeMultipliers](y^2 + x^2, [x^3 + y^2 - x - 1/3], [x, y], output = plot):

does not cause any errors.

Any chance to have "Evaluate->Remove Output From Worksheet" become active and usable when one is still running something in the worksheet?  May be in 2023 version?

This is something that has been missing in Maple for ages.

Maple definitely slows down when the worksheet becomes full of output (from print messages) when a command has been running for long time. Now there is no way to remove the output in the worksheet until the command completes which can take hours. May be this slow down because the scrolling/writing to the worksheet slows down, and this affects how long it takes to complete as the engine is waiting for the frontend to finish writing to the worksheet?. I do not know. I just know Maple slows down when this happens.

I do not understand why Maple can't implement this. Is there a tehnical reson which will make removing current output in the worksheet not possible while a command is running?

As we head back to school, I want to take a moment to thank all the math teachers out there who take on the demanding yet overlooked task of educating our children, teenagers, and young people. 

I'm where I am today because my calculus teacher, Prof. Srinivasan, was unwavering in her belief that my classmates and I could master any math topic, including calculus. Her conviction in me gave me the confidence to believe I could 'do' math. While Prof. Srinivasan made teaching look easy, I'm acutely aware that teaching math is no easy feat. Speaking with math educators regularly, I can appreciate how challenging teaching math is today compared to a decade ago. Not only do they have to teach the subject, but they must be able to teach it in-person and online, to a group of students that may not be up to speed on the prerequisite material, and in an era where disruptive technologies vie for their student's attention. No wonder math educators are so anxious about returning to the classroom this fall!

And while I wish I could abracadabra your worries away, what I can do is offer you the opportunity to use Maple Learn, a tool built to support the utopian vision of a world where all students love math. A world where math is for everyone, not just the gifted, and the purpose of math class is to explore and marvel at the wonders of the universe, not just get to the correct answer.

Slightly more concretely, Maple Learn is a flexible interactive environment for exploring concepts, solving problems, and creating rich online math content. I've seen educators use Maple Learn to help their students: 

• Grasp a definition or particularly tricky proof (for example, Formal Definition of the  Partial Derivative)
• Explore a concept and question their initial assumptions and beliefs (such as Is it an Odd or Even Function)
• Master a particular solving technique through drill and practice worksheets (Calculating Volumes)
• Work collaboratively on a math project (Designing a Roller Coaster)

I’ve talked to lots of instructors, in math, and in courses like economics and physics that use math, who have lots of ideas of how to engage their students and deepen their understanding through interactive online activities. What they don’t have are the tools, programming experience, deployment platform, or time to implement their vision. Fortunately, Maple Learn makes it incredibly easy to develop and share your own content, and all you need are your ideas and a web browser. But you don’t need to start from scratch. You can choose from an extensive, constantly growing repository of ready-made, easily customizable content covering a wide range of topics. I think you’ll be pleasantly surprised by how easy it is, but since we are well aware that instructors are extremely busy people, we also have content development services that can help you transform your static content into interactive lessons.

If you haven't looked at Maple Learn, or it's been a while since you last saw it, you can visit Reinventing Math Education with Maple Learn for more information, including an upcoming webinar you might be interested in attending and a special offer on Maple Learn for Maple campuses. And if you ever want to discuss ways Maple Learn might help you, or have ideas on how to make it better, please reach out. I'm always up for good conversation. 

And for all the dedicated teachers who are taking a deep breath and heading back into the classroom this fall, thank you.

Combing a Prismatic Joint component with an Elasto Gap component does not always provide correct results. Incorrectly combined (red mass below), a force is generated although the distance between the flanges is greater than the relaxed spring length. A force is exerted (instead of no force is exerted as stated here) on the mass which leads to a smaler deflection (expected are 9.81 m).

This happened to me although I connected flange_a to flange_a and flange_b to flange_b in configruation A bellow. Configuration B works with inverted flanges and configuration C works with inverted unit vector of the prismatic joint. By reversing the direction of gravity, configuration A becomes a valid configuration and configurations B and C become invalid configurations.

It seems that in invalid configruations the value of the  flange distance s_rel can have a large magnitude but is negative in sign which generates significant forces although there is no contact of flanges.

So far for the observations.

Would a change of the contact condition

prevent invalid configurations or do we have to live with it for principal reasons that I am over looking?

If so, I don't see a foolproof method to avoid invalid configurations. Instead, I can only suggest measuring the flange distance of the Elasto Gap component as in the attached. If negative values of large amplitude occur, the configuration is invalid.

Assuming that a beginner would connect intuetively flange_a to flange_a and flange_b to flange_b, there is a chance of 50% that the configuration is invalid (A instead of C). This is too much to be acceptable, especially since verifying results in complex assemblies is often not possible.

It is worth noting that the contact condition comes from the underlying Modelica component and not from MapleSoft.

Prismatic_Joint_with_Elasto_Gap.msim

According to Wikipedia

"In computing, a programming language reference or language reference manual is
part of the documentation associated with most mainstream programming languages. It is
written for users and developers, and describes the basic elements of the language and how
to use them in a program. For a command-based language, for example, this will include details
of every available command and of the syntax for using it.

The reference manual is usually separate and distinct from a more detailed
 programming language specification meant for implementors of the language rather than those who simply use it to accomplish some processing task."

And no, Maple's Programming guide is not a Language reference manual. This is a guide to how to program in Maple. But it is not reference manual for the language itself. i.e. description of the Language itself.

Examples of Language reference manuals are

C

Original C++ 

Python

Ada

Fortran 77

and so on.

Why is there no LRM for Maple? Should there be one? I find Maple semantics sometime confusing, and many times I find how things work by trial and error. Having a reference to look at will be good. 

I know for a language as large as Maple, this is not easy to do. But it will good for Maplesoft to invest into making one.

MapleSim is a mature product. The rich component library leaves little room for improvement for wide range of applications. It is understandable that latest product releases focused on specialized toolboxes and performance improvements.

Here is what I think could be beneficial for many users, which is not related to performance, but can help improve the user experience:

1. Crossing connection lines: A view option to render a crossing connection line with an arc at the crossing point of two connection lines of the same type. Right-click on a connection line might be enough.
    
   
   -> To avoid misinterpretations of routing in crowded model diagrams
    
2. Parameters: An option to populate or reset changes in the parameter pane to the parameter default settings view and vice versa
   
   -> When testing or optimizing a model, sometimes changed parameters should become default values or be reset. Doing this manually is error prone and takes time.
    
3. Component flip: Selecting more than one component including connection lines and applying a flip to all of them
   
   -> When building a model, it can happen that a nicely laid out arrangement of components needs to be mirrored or rotated in its entirety. Doing this component by component and connection by connection is a lot of work that can be saved by this option.
    
4. Initial conditions: An option in the view menu to highlight components where ICs have been changed from ignore to treat as guess or to strictly enforce
    
   
   -> ICs are set for many purposes. In addition to defining ICs needed for simulations, this can include extracting equations, testing different model states, or temporarily "immobilizing" a model during assembly, to name a few. Undoing a tentative change can easily be forgotten. Combining existing models that work on their own into a new more complex model often results in an overly constrained model that either cannot be assembled or does not simulate.
   In debugging a model, ICs of all components must be individually inspected. This takes time. A quick overview that shows components where ICs are not set to ignore would be very helpful in debugging models.
    
5. Undo Create subsystem: A reverse operation that inserts the contents of a subsystem into a parent subsystem.
   
   -> With the evolution of a model it is sometimes useful to exclude or include existing components from or to a subsystem. For this purpose, an undo create subsystem operation should preserve existing connections. A time saver.
    
6. Subsystem ports: An option to align a subsystem port to the drawing grid to remove “micro” steps in connection lines
    
   
   -> For perfectionists who do not have the time to learn (and remember) how to fine-tune at the component level
   
   Update: MapleSim 2022.2 has subtantially improved on this. This item could be removed from the list.
    
7. A history or log function of user actions changing a model, its parametrization or internal state.
   
   -> Often a model does not simulate at all or as desired after modifications. Restoring to a configuration that worked by undo only goes back to the last simulation performed. In such a situation, only reloading the latest file version and redoing modifications may restore the desired model, parametrization, or state. This takes time and migth be unsuccessful. A record of user actions would be a great help.
   History or log information in file format could also help MapleSim support to reproduce an error.

For me personally, reducing errors (4. > 7. > 2.) would improve the use experience much more than layouting aids (3. > 1., 5., 6.).

Hi, just some ideas for improvement!

- since MapleFlow uses Maple as its engine, more integration of MapleFlow and Maple would be nice. Some commands that work very well in Maple not always work the same in MapleFlow. For example, BodePlot plots magnitude and phase in Maple but plots only magnitude in MapleFlow

- a better Help documentation would also help. ?command/function works in Maple but not in MapleFlow. It's a bit anoying to have to open Maple just to get help documentation

- a lot of palettes are not enabled in MapleFlow. Again, it is a little anoying to have to open Maple to get some of the palettes copied and pasted into MapleFlow

Auto paste last entry

So maple uses % as the last expression entry.  My suggestion is to use Crtl+Space on the % command to re-display the last expression.  Yes one could easily use the mouse to select the last entry then Crtl+c and Crtl+v. 

Or maybe the command Crtl+Shift+L to auto paste last entry. 

**edit** actually I would prefer the Crtl+Shift+L option to auto paste the last entry.

** Appears to be a suggestion I made earlier https://www.mapleprimes.com/questions/148867-Is-There-A-Way-To-Recallrepeat-Previous

December and Maple 2021.2 have both arrived, which means that we can look forward to year 2022 and Maple 2022.

        What should we like to find new in Maple 2022?  Here follow a few suggestions, to which readers of Maple Primes can add.

        In my opinion the weakest feature of Maple 2021 is the solution of integral equations.  Even when this package was first introduced into Maple, a couple of decades ago, it was weak, applicable to only linear such equations.  A quarter century earlier, David Stoutemyer (a true genius and entrepreneur, originator of Mu-Math, Mu-Lisp, Derive and computer-algebra capabilities incorporated in calculators of Texas Instruments) had published code for non-linear integral equations, based on Reduce.  There is a Handbook of Integral Equations by Polyanin and Manzhirov that lists about 2000 solutions of integral equations.  Let Maple 2022 be the basis of a boast by Maplesoft for Maple to be able to solve 96 per cent of those equations, in the same way that Edgardo Cheb-Terrab can (rightfully) boast that Maple can solve 96 per cent of differential equations in a standard compilation.  Any differential equation can, apparently, be converted to an integral equation, whereas the converse is not true.  For this reason alone, the development of solution of integral equations should become a priority to assist users of Maple.

        Another area worthy of expansion and enhancement is the solution of differential equations in terms of Heun functions; that capability is already present, but working with those functions in their present form is difficult and slow.  The inclusion of related functions, such as Lame functions, into Maple is long overdue.  Although efforts have been devoted to the development of the physics package in recent years, culminating in a tremendous achievement of capability, only a few physicists in the world can appreciate that luxury, whereas the solution of differential, and integral, equations permeates all science and engineering. 

          What items are on your list of wishes for Maple 2022?