Hello @sand15! Your last 2D plot is quite aesthetically pleasing to look at with size=[1200,1200].

Thank you.

Hello @sand15! I made the one line of code change that acer suggested and it looks like it works!!

I had one question is this is more for my "feeble" eyes: Could you increase the size of the plots to size=[1200,1200]?  I can't seem to find where I can do that in your worksheet. 

Thank you.

P.S. I'll try to upload this updated worksheet but recently my uploads to MaplePrimes blog have been kicked out because it thinks I'm upload SPAM!! HA HA!!

@sand15  I downloaded your "plot-help_sand15.mw" and I get several errors that prevents it from completing the plots, for example:

z_period := 2*Pi/coeff(op(select(has, %, cos)[]), z) / 2;  # (division by 2 because solnum depends on core^2, not core)

  core := csc((225.6950581 - 0.8870967598 I) + 0.48387096 I y

     - 2.419354805 z)

    {|csc((225.6950581 - 0.8870967598 I) + 0.48387096 I y

       - 2.419354805 z)|, csc((225.6950581 - 0.8870967598 I)

       + 0.48387096 I y - 2.419354805 z)}

Error, invalid input: op expects 1 or 2 arguments, but received 0

And this one also:

display(seq(plottools:-translate(pat, 0, z_period*k), k=0..4)):

Error, (in plot/iplot2d:-Levels) could not evaluate expression
Error, (in plottools:-translate) invalid plot structure: pat

And finally this one:

pat := display(
           contourplot(A(y, z, r3, f, 2000), y = -3 .. 7, z = 0.. z_period, s3, grid = G,size=[1200,1200])
         , contourplot(A(y, z, r2, f,  100), y = -3 .. 7, z = 0.. z_period, s2, grid = G,size=[1200,1200])
         , contourplot(A(y, z, r1, f,   10), y = -3 .. 7, z = 0.. z_period, s1, grid = G,size=[1200,1200])
         , scaling=constrained
       ):

pat:

Error, (in plot/iplot2d:-Levels) could not evaluate expression

I would like to see your work complete successfully.  I have always learned about a lot about using Maple from your advice and suggestions.  Thank you.

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?