SIR model without DE's. 

Here are the equations. 

S_n = S_n-1 - ( ( S_n-1 / S ) * ( β * I_n-1 ) )  # Number of susceptible people

I_n = I_n-1 + ( S_n-1 /S ) * ( B * I_n-1 ) - ( I_n-1 * γ )  # Number of infected people

R_n = R_n-1 + ( I_n-1 * γ )  # Number of recovered people

γ - rate of recovery
β - rate of infection

So for your model 45 days (I've heard a recovery rate of 2 weeks) so the rate of recovery would be 1/45 = 0.022.  I think for the infection rate, for the U.S. it's doubling about every 2.5 days so here the rate is 1/2.5 = 0.4 (Australia's rate is actually just slightly less than 4days)

Hope this helps.

Here is a rope simulation in Maplesim. 

https://www.maplesoft.com/products/maplesim/ModelGallery/detail.aspx?id=121

n link pendulum is I believe what you would use for a rope.  There is a small discussion linked from here https://www.mapleprimes.com/questions/140946-Simulate-Cutting-A-Rope  which points to here https://www.mapleprimes.com/maplesoftblog/6889-An-Animated-Discussion-About-Pendulums

I'll also reference a paper here https://recipp.ipp.pt/bitstream/10400.22/8798/4/ART_MachadoTenreiro252_2015.pdf

This link might be more helpful http://www.pas.rochester.edu/~rrubenza/projects/RR_PHY235W_TermPaper.pdf

For your interest, here is a list of windows preview supported file types.  As you can see there are no maple supported file types

Documents: csv, doc, docm, docx, dotx, eml, msg, odp, ods, odt, pdf, pot, potm, potx, pps, ppsx, ppt, pptm, pptx, rtf, vsd, vsdx, xls, xlsb, xlsm, xlsx

Images: ai, arw, bmp, cr2, eps, erf, gif, ico, icon, jpeg, jpg, mrw, nef, orf, pict, png, psd, tif, tiff

Video: 3gp, m4v, mov, mp4, wmv

3D: 3mf, fbx, obj, ply, stl

Medical: dcm, dcm30, dic, dicm, dicom

Text and code: abap, ada, adp, ahk, as, as3, asc, ascx, asm, asp, awk, bash, bash_login, bash_logout, bash_profile, bashrc, bat, bib, bsh, build, builder, c, c++, capfile, cc, cfc, cfm, cfml, cl, clj, cls, cmake, cmd, coffee, cpp, cpt, cpy, cs, cshtml, cson, csproj, css, ctp, cxx, d, ddl, di, dif, diff, disco, dml, dtd, dtml, el, emakefile, erb, erl, f, f90, f95, fs, fsi, fsscript, fsx, gemfile, gemspec, gitconfig, go, groovy, gvy, h, h++, haml, handlebars, hbs, hcp, hh, hpp, hrl, hs, htc, hxx, idl, iim, inc, inf, ini, inl, ipp, irbrc, jade, jav, java, js, jsp, jsx, l, less, lhs, lisp, log, lst, ltx, lua, m, make, markdn, markdown, md, mdown, mkdn, ml, mli, mll, mly, mm, mud, nfo, opml, osascript, out, p, pas, patch, php, php2, php3, php4, php5, phtml, pl, plist, pm, pod, pp, profile, properties, ps1, pt, py, pyw, r, rake, rb, rbx, rc, re, readme, reg, rest, resw, resx, rhtml, rjs, rprofile, rpy, rss, rst, rxml, s, sass, scala, scm, sconscript, sconstruct, script, scss, sgml, sh, shtml, sml, sql, sty, tcl, tex, text, textile, tld, tli, tmpl, tpl, txt, vb, vi, vim, wsdl, xhtml, xml, xoml, xsd, xsl, xslt, yaml, yaws, yml, zsh

In Maple V R4 it is possible to specify multiple light sources.  This suggests that if one wants to deal with multiple light sources one must revert, at most, all the way back to Maple V.

How is it possible that as Maple gets more powerful we loose functionality?  And it's not just one version, it's many of the new versions where multiple lighting is not possible (if it is, please show me the workaround I am very interested if there is one).  I'm not saying Maple V is more powerful than maple 2019 but with respect to lighting .. it actually is! 

A[..,1]

          [4, 9, 6]

A[..,2]

          [2, 1, 8]

You could try this option here

https://www.mapleprimes.com/posts/200446-3D-Implicit-Plot-With-Scaled-Axes 

I'm actually not sure if this will work, don't have acces to Maple. 

Try th option LINESTYLE(1)

The answer of your expr is never -'ve.  So sign(expr) will give 1 and not -1.

Yes, if you use back quotes around your primed variable.

`A'`:=t

You can select cells and merge using options with the left click section by section. 

Here is a roadmap - a template if you will

`#mscripts(mi("H"),none(),none(),none(),none(),mn("3"),mn("9"))`[7]^2

Easier, you could do ...

assume(x>0)

simplify(combine(f,trig))

If you mean the yellow line isn't touching the green line, it's because your viewing area you set for each plot doesn't allow the values for the green line to reach the yellow line, or vice versa.

You've combined the graphs fine with display.  If you think they should intercept, then you need to solve the two equations in the yellow and green pots for x and use that as one of your extents in the range of your plots.

Alternatively as a for loop, (albeit using the list way is not efficient)

a:=[]:
for i in A2 do
  for j in A1 do
    a:=[op(a),j/i]:
  end do:
end do:
print(a)

Starting with the position vector

r2:=<x1(t)|y1(t)|z1(t)> #your r2 position row vector as a function of time.
T:=Matrix(3,3,[[T1,T2,T3],[T4,T5,T6],[T7,T8,T9]]) #your transormation matrix
r1:=r2.T #your r1 position vector
Since the transformation matrix isn't itself a function of time in our example
d(r1)/dt is just d(r2)/dt .T    since d(T)/dt is zero.  and then the acceleration is simply d(d(r1)/dt)/dt

Does this answer the first part of your question?