## 110 Reputation

9 years, 290 days

## Interesting common problem with animate(...

Hi Robert,

I recently posted a similar call (in fact I think identical except theta instead of t for the animate range variable) and had an interesting error on the range.   That was solved by forcing an evalf on the realcons Pi/2, (using the Greek Pi tablet click).

I am now interested in the vectorCaculus form.   My main interest is to visualize a vector's transformation as it applies to robotic frames and transformations.  Watching in 3D a rotation is really key than seeing a start and finished view on how the transforms work and then the math for 'exp' and Log of velocity transforms, screw, transpose, twist, wrench, etc.

At the moment I am trying to see a two rotation sequence in animate where two rotation matrices are applied to the starting vector, [P].   Using simple matrix multiplication of the rotations matrices inside the arrow function for "what I think is the operation's output" of a two column vector of position for the animation - But, did not achieve the final expected position.

I am wondering now if the order of operations is the problem and the frame-by-frame vector is not completing properly.

P.S., love discovering these tidbits, but often wonder the challenges of finding these when debugging problematic outputs.  The matrix math for frame transformations is a challenge in and of itself and I am pre-planning a proc() for the 4x4 and other transforms (skew-symmetric).  Hoping Maple has this already in a package that I've yet to discover.

All thoughts welcome.

Bill

## Thanks both, unassigned...

I agree with @acer that the 0 = 0..Pi/2   showed the assignment earlier to test static.

When I commented the Theta := 0 out the error still persisted.   When I typed evalf(Pi/2) it worked.

I did re-rerun with 1.) an unassign in variables tab - same error; 2.) commenting out the initial assignment-same error; and lastly 3.) incorporated the evalf(Pi/2) - worked.

I do appreciate the difference in the Upper Pi vs lower pi.    In most intances I started with the greek panel usage of theta and Pi. I don't often type Pi or pi, but recognize the difference.

All said, just for final thought - 4.) I took evalf(Pi/2) and removed it to force the numeric with Pi/2.0 (hint by Earl of what needed to be there) and just hit run with Pi/2 and it DID NOT Error out.

I suspect a persitence existed or maybe a typo for the pi?  I am not sure now.

It is working and I am now getting good results moving into 3D vector animated rotations.

Thank you both.  Just wanted to document for future users that may have similar problems.

## I just used evalf(pi/2) in the range and...

I just used the evalf(pi/2) and the animation sequence works.

Not sure why Acer comment didn't resolve, but Earl's evalf did work.

Thanks to both for the assist.

Bill

## eval to 0 ?? for animation problem...

Is 0 an appropriate cos or sin value?

I trialed the static version using theta = 0 and got the first frame's presentation correct by function.

I unassigned in the variable list the theta = 0 assignment.   I also just commented this assignment out with # symbol and re-ran but get same error.

## Gratitude...

thank you both @acer for your replies.  Very clear and helpful with improving capability and usage of Maple.

Regards,

Bill

## Couple questions...

Thanks again,...  Can you clarify a couple commands please and sorry if this might be elemental stuff.  I understand the convert to list for the column labels and this was probably my first error of why the array text was error'd out trying use the columnlabel option in an earlier attempt.

1.) The original array elements were of a text(string) type, but you use subsindets to "transform" the list elements to string.  I used whattype on the command and see both (array and list) return strings for the elements contained inside.  Why was this necessary other than just using convert to turning the array into a list argument?

(P.S., I like the u arrow operator vs in-string tools to get the characters after 5th.)

2.)  Can you explain the "transformer" and "rest" arguments as to how you know a valid transformer operator (in this case 'string') and the second argumant option to "feed it" with the u->u[5..]   vs it just acting on the elements??

- I presume a different substring operation could have been used to remove chars 1-4 ?

Thank you,

Bill

## Axis manipulation...

Thank You.   Great showing of the command usage to manipulate the axis.

So glad you're a subject matter expert on Maple on this forum.

Bill

## How neat...

@acer

Thank you.  You always have the hidden gems of commands.

so much appreciated!

Bill

## Please try this static version of the ar...

Here is the worksheet

Bill

 >
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 (1)
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 (2)
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 (3)
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 (4)
 >
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Can I statically post the array3 which is an excel import (ExcelTools) without having to provide the full sheet and the file management commands to get the file data into the array?

I don't think I can post the excel file as is.

Thanks,

Bill

## Fantastic...

This is a great worksheet and very illuminating of the mode responses.  The animations showing the complex motions is quite amazing.

Thank You,

Bill

## Thank you, do you have links?...

Your original email said to contact you to know where best to get these for Windows.  The Git seems to be Unix based mostly (?).

Bill

## I am interested for use on windows10 pla...

Hi Joe and thanks for replying.

I have shied away from emacs or vi(m) as unix based.  My Ubuntu is ver 14.04 and is so old to upgrade its a nightmare on dual boot.   I am about to overhaul the dual boot and remove the Ubuntu in total just to fix windows 10 issues.  It never operated well and spent many hours with the "

`sudo apt-get update`

process to get past the ancient and new secruity checks that fight each other.

My day job is to use code to do useful things, not chase OS upgrades that obsolete functions or add features never needed, or to close a security holes that broke it in the first place..

PS., Windows does SSDD   ...Sighing much.

Any assist here would be greatly appreciated and thanks again in advance!

Bill

## upload try again, but think I may have f...

The first time I used this worksheet I used a length command for the vector length and it worked fine.

Looking back I should have used ArrayTools:-NumElems for the single column vector.