Hello @rquirt!  Don't forget you need to load the numapprox package for the Pade approximation.

I keep trying to upload the file which I do my Pade approx in a control systems analysis but Mapleprimes REFUSES to accept it.  I don't know why.  It is just a *.mw file.  Nothing fancy.  Mysteries abound!!

Dave 

P.S.  Have a nice Thanksgiving Day wherever you reside!!

@WD0HHU 

Try putting a 4 in the numerator and a 4 in the denominator.

Hi @acer! I keep trying to upload a *.mw file and it won't accept it.  I am not getting a "warm-fuzzy" that this blog is accepting it.  I don't know why. 

@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?