@rquirt 

I'll try again.  I have to go to another computer.  So it should be here shortly.  I'll shorten the name.

@rquirt 

ZOH := (tau, PadeNumerOrder, PadeDenomOrder) -> normal((1 - pade(exp(-tau*s), s, [PadeNumerOrder, PadeDenomOrder]))/(tau*s))

F1 := (tau, PadeNumerOrder, PadeDenomOrder) -> map(sort, pade(exp(-tau*s), s, [PadeNumerOrder, PadeDenomOrder]), s)

Test these out.  The "tau" input is the time delay.

Download Pade_Approximations_for_Delays_&_ZOH_For_AEHF_Roll_Axis.mw

@rquirt 

Hope this gives you some help!

@rquirt Take a look at this & I'll search my Maple worksheet files to give you hard example on using Pade approximations for delays in control systems 

@sand15 Thank you very much for your great suggestions.  I have reworked my simulation at the moment and I will definitely incorporate all your suggestions going forward.  I have been struggling with units because dynamic pressure q are (kg)/(km^3*sec^-2).  Also, since the Mars gravitional parameter mu is in (km^3/sec^2), I am trying to keep everything with kilometers for frontal area of the sphere.  According to Rouben below, I am using gamma for flight path angle and so I have made gamma local.  In a simulation like this dimensional analysis can go a long way in making sure you get the correct results.  Rho is the atmospheric density model for Mars and your value for the density of Mars at the surface is a currently accepted value by orbital flight mechanics folks.  One other point, if the cofficient of drag is low and assuming you want to land -- hopefully not crash (!) on Mars -- there are combinations of Ballistic Coefficient and certain entry conditions where by you won't crash but actually enter an orbit around Mars!  But because of the weight restrictions, a single Ballistic Entry is used a lot assuming there is a gigantic wind storm on the surface of Mars because with this approach you have only one shot!! This is such a cool problem as we potentially could be landing astronauts on the surface of Mars in the next decade.

@dharr I have seen this happen to me.  I then have to go the folder that the Maple worksheet and open it that way. 

Something is "stinky-in-Helsinki" with this new interface in Maple 2025.1 

Hello acer! I took what you show here & found these images of Mars & Earth

and I have embeded them in a sphere using the plottools as you will see.  

Warning: These are big image files being downloaded from a NASA website so be patient!!

Hello, I know this won't make that much of difference but I was at a baseball game between the Colorado Rockies and the LA Dodgers and the Colorado Rockies pitcher threw a 95 mph fast ball to strike out the LA's big time slugger.  He threw 3 pitches in a row at +90 mph and the BIG slugger didn't have a chance.  The stadium went crazy when he was called out.  My favorite MLB baseball experience!

This might have been a strategy to shoot the wolf that is killing the goats.  Sacrifice one goat to same the many.  Do you want to include that possibility?

@Joe Riel That is EXACTLY what I needed to know!!! I must have some how, some way, turned off this option.  I can't possibly remember how I did that, but I have asked this question at least 6 times on this blog and you are the only one that has not only read my question but gave me the information I need.  Thank you again!! I need the capability to stop something that will run forever when I don't want it to.

What other good things are on that View tab that I need to know?

@FDS Thank you for your reply, but I have Maple 2025.1 and I am running a worksheet and I don't see this in the lower left side of my worksheet.  Do you have to do something in Options or Tools tab to make it appear? I can't figure it out.  I have one continuous "gray" bar that runs from the left side of my monitor to the right side at the location that you say these symbols exist.  I really need at time sto use that "Stop Execution" command and other than bring up the Task Manager and killing the process, I don't know how to stop Maple from being in an infinite "do" loop.  

I have asked this questions several times and nobody seems to know what I mean.  Would you like me to include a screen shot?

Thank you.

@epostma 

I cut and pasted your procedure above into a my Maple 2025.1 version into a new file and tried to run your example and I get an error message: "Error, invalid local declaration".  And it seems to be pointing to this line of code inside your procedure:

local (pow1, powN):= selectremove(type, powers, [':-anything', 1]);

I am not sure myself what is wrong with this line.  

Do you have any ideas?

@TechnicalSupport My Status Bar is just a long grey bar that runs along the bottom of the Maple worksheet.  I don't have the objects that you show are that your BIG GREEN ARROW points to.  They are missing.

@Rouben Rostamian  Good idea!!!

I don't see the the "Stop Execution" Icon that exists in Maple 2024.1 and I don't have the two little buttons in the lower left hand side on Maple 2025.1.  How do I stop execution without having to go to the Task Manager and killing it that way and losing everything?  Above is Maple 2024 and below is the bottom of Maple 2025.1 and there are no little buttons -- one of which is the supposed to be the "Stop Execution" button.  Where did those guys go?  

I keep asking this question on this blog and I either have my question deleted or ignore