johnksellers

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1 years, 97 days

MaplePrimes Activity


These are replies submitted by johnksellers

@Carl Love 

Even if the install log immediately uses mode win32, it is to install Maple with 64-bit words. 

'nuff said

 

 

@Carl Love 

Is it definite then that I downloaded the 32x installer?  I've seen programs on 64x Windows systems that involk Win32.

@acer 

escape helps better than other methods that were suggested, and from your lead I've checked corresponding docs.  I found Crtl-space but escape is still a bit better.  However escape is an awkward solution.  It is puzzling to me that I haven't been able to find a better solution.

I wish I could dig down to where escape is implemented and poke around there.  There ought to be a way to improve on that, unless there is an existing solution I don't know about.

Here is how awkward escape is.  I ended up with this situation:

"(((R__xy(theta__xy)) . (R__yz(theta__yz))) . (R__wx(theta__wx))) . (R__zw(theta__zw))"

A combination of escape and the keyboard right arrow enabled me to fix it.  But that means left arrowing through the whole expression and then applying escape 8 times at the right junctures.  That is not ideal and is a time waster, and is a pretty poor substitute for maybe doing a single operation or menu pick to do the whole document.  But it kept me from being stuck and not being able to do it at all, and I am greatful for that.

I'm going to keep the question open a bit until I am convenced there is not a better answer somewhere.

 

I got under my belt a couple of simple tricks for converting single fields.

I was thinking more about the situation when I have done a search and replace and there are a number of fields I would like to be converted.

I take it that there is not a general function for going through a long document and converting all the active fields to the MATH symbolic form?

@acer 

I'm using Maple 2020, and you don't really want to see the input because everything cancels out except, w,x,y, and z, and the simplication needed is a simple product of differences which is completely cononical and disregards any external conditions.

I'll show it to you anyway, but it isn't really relevantand to the problem, which has now been solved.

Although considering the whole context, any fix is just a patch.  I shouldn't have to refer to any student package for a fix that is an oversight of Simpify.  All versions of Simplify, including the perported compacting versionl all return the results with some of the products of differences expanded....  I am not about to use the Student stuff if I ever decided to publish anything.  (I am so new to Maple that I don't know how to explore Simplify in detail to see if I have missed anything).

Otherwise, simplification seems to work pretty nice for what little I have seen it.  It has fixed some very hairy 5x5 matrices for me.

So here is the what "other side" looks like per your request:

 

@tomleslie 

Thanks,

Your answer enabled me to find the better solution:

      HVNorm := A -> LinearAlgebra:-Norm(A[() .. -2], 2, conjugate = false)

HVNorm stands for Homogenious Vector Norm.

BTW The intent of the extra dimension is that Homogenious transforms have an extra degree of freedom so all the variables can be scaled with the transform remaining invarient.  By normalizing the last row of the Metrix to  0 .. 0 1  and the vector to 1, all division is removed from all the calculations except for division by 1.  This means no division by zero or losing percision because of scaling problems brought on by a string of transform multiplications.  Everything is automatically scaled so that results in the the denominator before and after all calclulations is always 1.... you can build a whole CAD system and never even use division per se.

---end of "aside"

I should not have mixed metafores.  I know bettter. 

VectorCalculus and LinearAlgebra have things in common, but they have their own courses, and this will always be the case unless everyone in the World talks to everyone else on all matters.  I don't see that happening any time soon.

Although, a good approach to fixing such differences is by backing off to look at the larger picture to see where they fit in relationship to each other.  I don't know enough about Maple to have any context on this.  I've only been in the envrionment 3 days so far.  I am on trial version and thinking about getting an individual license.

Sincerely,

 

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