Adri van der Meer

Adri vanderMeer

1350 Reputation

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14 years, 277 days
University of Twente (retired)
Enschede, Netherlands

My "website" consists of a Maple Manual in Dutch

MaplePrimes Activity


These are answers submitted by Adri van der Meer

Perhaps your TeX-machine can't find the stylefile maplestd2e.sty?

format := "%+03.1f %+04.2Zf %+04.2f \n":

In the first equation you have the conflicting ICs (D(x))(0) = 0 and (D(x))(0) = v0
The second must be (D(y))(0) = v0, I suppose

  • Write the differential equation in the right way:
      diff(phi(zeta),zeta) = psi(zeta), 
    diff(psi(zeta),zeta) = phi(zeta)/alpha + beta*phi(zeta)^3/(3*alpha*c)
    indicating that φ amd ψ are the dependent variables and ζ the independent variable
    (Choose Tools → Options → Display → Input Display: Maple Notation to get full control over your input)
  • Assign a numerical value to the parameters α β and c
  • Give some initial points in the phase plane
  • Perhaps ?DEplot is better in this instance

With no more information on the nature of Record(...) I can only refer to ?fprintf

plot( [[x,2*x^2,x=-1/2..0], [x,1/2-x,x=-1/2..0],
      [x,1/2-2*x^2,x=0..1/2], [x,x^2-1,x=0..1/2]] );

see ?plot,parametric

Format list for each column of the matrix:

formats := "%+03.1f %+5.3e %+07.4f \n":

(mind the newline character at the end)

B := convert(A,listlist):
for i to nops(B) do fprintf( terminal, formats, op(B[i]) ) end do:

First possibility: you want to plot the derivative of x'(t), that is to say: the derivative of a numeric procedure. I suppose that odeplot is not designed for that. So use the option output=listprocedure:

sol3 := dsolve({DE1, DE2, ICs}, numeric, output=listprocedure );
v := subs(sol3,diff(x(t),t));
st := time(): plot(D(v),0..3); T := time() - st;

Faster is to calculate timeseries for x(t) and v(t) and use a(t) from the differential equation:

solve( DE1, diff(diff(x(t), t), t) ): subs( {m(t)=m, x(t)=x, diff(x(t),t)=v}, % ):
a := unapply( %, t,m,x,v );     #acceleration as a function of t, m, x and x'
sol2 := dsolve({DE1, DE2, ICs}, numeric, output=Array([seq(i,i=0..3,0.001)]) );
   # sol2 has two parts: a list with the names of the variables and a matrix of calculated values
plot( <sol2[2,1][1..-1,1]|a~(seq(sol2[2,1][1..-1,i], i=1..4))> );

You have two times " = 0 ", so

solve([eq1,eq2],[x,y]);

If you want to use the option coords = polar, then you must use the "normal" plot-command, to plot r(theta).

q1 := dsolve( {sys1, theta(0)=Pi, r(0)=2}, numeric, output=listprocedure);

This gives you numeric procedures for r(t) and theta(t).

Theta := subs(q1,theta(t)): R := subs(q1,r(t)):
plot( [R(t),Theta(t),t=0..10], coords=polar, axiscoordinates=polar );

The second argument of writedata must be of type {set, hfarray, list, matrix, array(1), list(list)}, and L is a table. But the result of evaluating a table is its name, and not its content (to get this, you must do: eval(L);) and that is wthe error message seems to say that L has no value.

I think the type "table" is not what you want, because a table consists of a set of indices and a set of corresponding entries, and that is probably not what you want to store.

To make L a list (for example):

L := [seq(i^2, i=1..3)];

If you really want to write the table, that is: both the indices and the corresponding entries, do:

LL := [seq( [i,L[i]], i in op~( [indices(L)] ) )];

Mind the tilde in the op-command.

Use the option gridrefine=6 or so in,implicitplot, and be patient

?textplot

It is not quite clear what your maplet is expected to do. After typing: "1,2" in the Input Box, clicking the button "addition" results in the value 3.
If you want entering digits by pressing the number buttons, you must use at least different mames of variables to store the values. Etcetera. I'm affraid that a radical redesign of the program set-up is needed.

Perhaps you mean output in uξ-notation?

restart; with(PDEtools):
declare( );
du := diff(u(xi),xi,xi);

gives the desired output; and

OFF;
du

prints the second derivative of u in the normal layout.

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