Carl Love

Carl Love

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11 years, 192 days
Himself
Wayland, Massachusetts, United States
My name was formerly Carl Devore.

MaplePrimes Activity


These are replies submitted by Carl Love

@emendes A DataFrame is an object (in Maple's implementation of object-oriented programming (OOP)). When a procedure exported by an object's "master" module is applied to that object, the procedure is automatically recognized as the module's export without needing with or a module prefix. These procedures are called the object's "methods", which is an OOP term that I think is ridiculous because there's no need for a yet another new word for "procedure". So, Tabulate is a DataFrame method that simply invokes DocumentTools:-Tabulate.

@WA573  @Rouben Rostamian  Certain assumptions tacitly imply other assumptions. Of couse, any mathematician knows that. What I specifically mean is that certain assumptions formally made in Maple cause other assumptions to be formally (but tacitly) made. A common example is that assuming a < b is equivalent to assuming a < b, a::real, b::real. So, assuming a < b will cause conjugate(a) to be treated as a, and likewise for b.

I just mention this "for what it's worth"; I don't know if this knowledge can help to explain the OP's situation. I'm just saying that while making that assumption may cause confusion for a human reader if it's done without comment, it doesn't cause any confusion for Maple.

What do you mean by "do this is by using the Tabulate (plain command and not from DocumentTools) function"? As far as I can tell, there is no "plain" top-level Tabulate, only Tabulate commands in packages DataFrameDocumentTools, and StringTools. Are you converting a Matrix to a DataFrame before using Tabulate?

I have had that bug on my computer before (many times), but I haven't seen any reasonable explanation for it, nor can I reproduce it. It doesn't seem to be widely reported. It is intermittent. When it's happened to me, other symbols also change, such as + and - becoming and K. Does that happen for you? And when it happens to one of my worksheets, all open worksheets are affected. If I save my worksheets and close the entire Maple session, the bug is gone when I restart Maple---the errors are not stored in the saved worksheets.

@Mike Mc Dermott If I made a suggestion in this thread, it seems to have disappeared. I recall thinking about a suggestion for this thread. What is the thing that you think is "even better"?

@JAMET Using that code, I do get [4, 18/5, 1].

@Rouben Rostamian The YouTube video that you linked is an excellent demonstration and explanation of the motion of balls on rotating platters. And it explains why certain patterns can be explained entirely by the moments of inertia.

If there's no friction, then why would the carousel have any effect at all on the cube, regardless of whether or not it's self-propelled?

I think that using the principles from, say, a first university physics-for-majors course, the only approach to the problem is for it to be a round object (cylinder or sphere, solid or hollow) rolling without slipping. The moment of inertia of the object comes into play, which can be easily calculated for spheres and cylinders (uniform solid or hollow).

Do you intend for &x to represent the vector cross product of two 3-D vectors? That's what &x usually means in Maple. Or do you want the product of a Matrix, the inverse of Mat, with a vector?

@mmcdara I think that the answer to both of your most-recent questions is that the Statistics package was written before Maple formally had objects, and RandomVariable would greatly benefit from having its code refactored as an object.

@FDS I tested the 3rd line of code from my Answer in 2D Input, and it works. Here it is applied to row selection:

restart

NULL

M3 := Matrix(4, 3, {(1, 1) = 34, (1, 2) = 67, (1, 3) = 1, (2, 1) = 35, (2, 2) = 80, (2, 3) = 1, (3, 1) = 45, (3, 2) = 78, (3, 3) = 2, (4, 1) = 56, (4, 2) = 99, (4, 3) = 2})

Matrix(%id = 36893491144047469140)

M3[select(`~`[`=`](M3[() .. (), 3], 2), [`$`(1 .. op([1, 1], M3))])]

Matrix(%id = 36893491144047452636)

 

NULL

Download select.mw

@Laurenso A warning is not an error. After receiving the above warnings you can proceed to run the procedure. The warning can be avoided by putting local j, k; in the locals area of the procedure.

Please repost the Question (by editing this Question). If someone thinks it's a duplicate, they ahould post some evidence of that, such as a link. Anyway, I think it was a great Question.

I hate all such meta-tags, I never use them, and I wish that they were forbidden! If a Moderator is sure that something is a duplicate, they should delete it. Anything less is sniveling passive aggression.

I don't recall ever seeing a duplicate to your original Question.

I don't understand what mathematical principle allows you to discard exp(x^2) as being "not real". Perhaps you want to discard it because it can't be 0? That's a separate issue. If that's what you mean, let me know.

While it's true that real is not a Maple type, it is a Maple property, and properties are the primary modality of assuming.

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