@Scot Gould   That is informative and explains some issues I have been having when using sol(t) in subsequent steps in my program.

@acer Adding  "value" makes all the difference.  I would think it would be the default. I had no idea what was going on.

@acer    Wow!  There are certainly some subtleties to using Maple.   There is not even a link  to "known" in the Maple Help.

@tomleslie 

@ecterrab Update worked OK this morning. 

@ecterrab  Wow!   When define by passing tensor equation, contravariant automatically defined.   I thought it should be and was thus surprised when it wasn't when I defined it by passing tensor and then assigning values.   I hate to confess  my ignorance but I spent many hours trying to get this contravariant tensor.  

Thanks so much for your help!

@acer Fantastic!!  Physics package update successful.

Using the older version, could not duplicate all the details in Dr. Cheb-Terrab's  Maple writeup "Vectors in spherical coodinates using tensor notation".   For example, contravariant tensors were improperly written with subscript,  Now, correctly written with superscript.  

Did you link to update?   I cannot find it. 

@ecterrab   I do not think your efforts in, seemingly, single handedly, developing the Maple Physics Package are widely enough appreciated.  It is my hope that some adventurous physics professor will develop a complete set of courses based on it. 

Thank you so much for your  quick response.   I did rerun the whole program and still had subscripts.  However, I then updated the Physics package and now it works OK.

I had just purchased Maple 2020 last week (specifically to run your tutorial) and, since, during the installation, it said it was installing updates, I assumed  I had the latest version.   Sorry for troubling you.

I would like  to thank you for making the effort for creating this tutorial. It is just the kind of information that I have been looking for.  For example, I had not previously figured  out how to just use 3D spatial dimensions (no time).

I am going to presumptuously make a minor suggestion.   For me (and I assume the typical user of this tutorial), it would be helpful if you did not make such an effort to get concise code (eg, one line), and instead used a few more lines.  I find that the tricks you use in this code are confusing and not helpful for learning the basics of the Physic package.  However, this is a very minor complaint, and, please, provide more of these Physics tutorials if you have the time.

When I try to reproduce this, I get subscripts (ie, covariant tensor) at line 2.2

I am continually amazed at how helpful this site is.

I have been struggling to learn all the complexities of "Simplify".    Both of these solutions are very helpful

Thank you Dr. Cheb-Terrab.  I have now looked at that mini-course and will definitely work my way through it.  It looks like just what I am looking for but, as you state, a greatly extended version would be a wonderful addition.  You are to be commended for making the effort to develop this package.  I became interested in it when I started using some relativistic tensor calculations.  The tensor notation and routines in your package are so superior to anything else that is available, there is no comparison. (A whole course on general relativity using the package is what I dream of).   I often have students asking me why I am using Maple rather than Mathematica.  This Physics package is the best example. I find it hard to believe that some enterprising physics professor has not developed an entire course around this package.  If so, it would not be that difficult to put the video of the lectures online along with worked problems using the package, etc.