Also, it is possible to do that as

`#mover(mi(x),mo(^))`;

I wonder whether that works on J. Tarr's system, or not. Another interesting question is whether mover accepts accent="true" option, see mover in MathML, and if it does, then how to enter it? Personally, I was quite disappointed that Maple instead of using (La)TeX in the input for 2d-math output (that would be much shorter, by the way), chose MathML. Now, it appears that also only a small part of MathML can be displayed, and in a changed form - as in the mover examples in this thread. It is slightly shorter than plain MathML that would look like

<mover><mi>x</mi><mo>^</mo></mover>

but then LaTeX would be much-much shorter. It's hard to see the point of changing MathML format for doing that. By the way, changing of the MathML format to "Maple MathML" format leaded to adding quotes - so that the parentheses, for example, can be displayed. There is no such a problem with parentheses in MathML, because MathML is using angle brackets. __________ Alec Mihailovs http://mihailovs.com/Alec/

Did you look at the VectorCalculus package? __________ Alec Mihailovs http://mihailovs.com/Alec/

When you use html (default) input format, you have to replace < and > signs with &lt; and &gt; correspondingly, otherwise the part of your post may disappear, as it seems to happen with your post. __________ Alec Mihailovs http://mihailovs.com/Alec/

The second question is answered in ?contourplot, it can be done by adding contours=[5,10,15,20] in the contourplot command. The contours can be labeled either by using textplot, or as in the following example, with legends,

with(plots):
colors:=table([5=blue,10=green,15=red,20=black]):
display(seq(contourplot(x^2+y^2,x=-5..5,y=-5..5,
contours=[i],color=colors[i],legend=sprintf("%2d",i)),
i=[5,10,15,20]));

            

The table with colors and the format of the sprintf command should be adjusted according to the level values. __________ Alec Mihailovs http://mihailovs.com/Alec/

As I said earlier, use different parameters for cirkel and ellips. If you use theta in cirkel, use phi in ellips. __________ Alec Mihailovs http://mihailovs.com/Alec/

It worked OK for me, with corrected initial conditions

odeqs:= {diff(N(t),t) = a*N(t) - b*N(t)*P(t), 
    diff(P(t),t)=c*N(t)*P(t) - d*P(t)}:
a,b,c,d:= 3,2,1,1/2:
initConds:=[[N(0)=(5/3),P(0)=(10/9)]]:
DEtools[DEplot](odeqs, [N(t),P(t)], t=0..100, N=0..7, P=0..7, 
initConds,stepsize=0.05,scene=[t,N(t)]);

__________ Alec Mihailovs http://mihailovs.com/Alec/

In addition to Ctrl+Shift+" that puts a hat too high in the output, the following also can be used, `#mover(mi(x),mo(^))` __________ Alec Mihailovs http://mihailovs.com/Alec/

For example, as I did in Will's blog, A Little Humour. __________ Alec Mihailovs http://mihailovs.com/Alec/

If you read ?sort, it is said there that in such cases the sorting function has to be provided. In this example, either is@`<` or evalf@`<` or `<`@evalf can be used, or with replacing of `<` with `>`,

sort([1+sqrt(3),1-sqrt(3),0],is@`<`);

                             1/2          1/2
                       [1 - 3   , 0, 1 + 3   ]

__________ Alec Mihailovs http://mihailovs.com/Alec/

axis[1]=[color=white,location=low] See Hiding the axis scale thread. __________ Alec Mihailovs http://mihailovs.com/Alec/

Since the solution depends on 2 initial conditions and t, 3 variables, it can't be plotted using plot3d (that depends on 2 variables.) It can be plotted as animation though, with using either t, or one of the initial conditions as the animation parameter. __________ Alec Mihailovs http://mihailovs.com/Alec/

soln(theta) gives a list of 3 equations, [theta=..., r(theta)=..., diff(r(theta),theta)=...]. It is not a good argument for the polarplot command. See the examples in ?polarplot. __________ Alec Mihailovs http://mihailovs.com/Alec/

See ?mpl In addition to creating mpl files in a text editor, they can be also created in the worksheet and then saved using .mpl extension. For example, you can write a procedure f, test it, and then save as

save f, "f.mpl";

It is not the best way of saving procedures though. Also, it is not a good idea to save the whole worksheet's input by using File - Save As and selecting Maple Input in the Save as type field in Classic Maple and similar to that, just with Export As instead of Save As, in Standard Maple. That often leads to errors in reading the mpl file, similar to what you get. Probably, you had something like ?plot in the first line of your worksheet, and such things can not be in the mpl file. Also, expressions with % may be interpreted wrong, and some other expressions, so it is better to avoid doing that. If the mpl file was created by using save command, it can be read using read command without errors. __________ Alec Mihailovs http://mihailovs.com/Alec/

In the Standard Maple worksheet with 2d-math entry mode, type thet, click Ctrl+Space (+ means both of them at the same time) and click theta in the tooltip. Then, click Ctrl+Shift+" (3 buttons at the same time), type .. and click right arrow. That produces what you wanted. To check that, click Enter and you'll see in the output the second derivative of theta over t. __________ Alec Mihailovs http://mihailovs.com/Alec/

First, projection,

Itouch50 := -0.4058074876e13*sqrt(1.+h)/
(sqrt(ts)*(-500000000.0*ln((625.+125.*h+25.*h^2+5.*h^3)/h)*
sqrt(1.+h)+587311661.7)):

p:=plot3d([Itouch50,ts,h],ts=0..10,h=0..4):
plots[display](plottools[project](p,[[0,0,0], [1,0,0], [0,1,0]]),
orientation=[-90,0],axes=normal);

Multiple projections can be done the same, just put all of them after (or before) p in the display command. If you don't need 3d-view of the projection, it can be done even more simple, as

plots[display](p,orientation=[-90,0],axes=normal);

or even

plot3d([Itouch50,ts,h],ts=0..10,h=0..4,orientation=[-90,0],axes=normal);

Next, the lower side of the projection is obviously given by equation y=0 because free of y part of the denominator is approaching infinity when z is approaching 0. The upper side of the projection can be found through

solve(x=Itouch50,ts);

Optimization:-Maximize(%*x^2);

      [                      6                           ]
      [2.16092450945321750 10 , [h = 2.62565595367750504]]

y=%[1]/x^2;
                                            6
                      2.16092450945321750 10 
                  y = -----------------------
                                 2           
                                x

__________ Alec Mihailovs http://mihailovs.com/Alec/