I just noticed that Maple 2020.1 (but not plain 2020) has an issue with print to PDF if you have a plot3d on a page.

Anything after the plot3d output on the same page of the PDF file is simply not shown.

The issue seems to be with both Windows and Mac which makes me suspect its a Maple problem.

Any info on this? Any workarounds? We have students with written exams in a week so its a bit annoying.

Tried several things to get a neat grey box with Maple text in it 
What to do for making this ? 

Hi everyone...

How can anyone help me in the attached file? I want to know how the equation of the system turned into a dimensionless

dynamical system?

I did not know about these before. Was looking at 

https://fr.maplesoft.com/support/help/Maple/view.aspx?path=repository/management

And wanted to display the actual values of $MAPLE,$TOOLBOX, $VERSION,$HOME gives about. 

But everything I tried does not work. 

anames('environment');
getenv("$MAPLE");
print("$MAPLE/toolbox/$VERSION/$TOOLBOX/lib")

Where are these things defined and how to display them from inside Maple to see where they point to?

Maple 2020.1 on windows 10

dAlembert ode has the form

https://fr.maplesoft.com/support/help/Maple/view.aspx?path=odeadvisor/dAlembert

Which also agrees with textbooks and Wikipedia

https://en.wikipedia.org/wiki/D%27Alembert%27s_equation

So the ODE should have   x  in there (the independent variable).  

Then why  in the following, when I give Maple ode of form   y=f(p)+g(p)  it says it is d'Alembert? notice that there is no x in there

restart;
ode:=y(x)=ln(cos(diff(y(x),x)))+diff(y(x),x)*tan(diff(y(x),x))

DEtools:-odeadvisor(ode)

I am not saying Maple is wrong, as I am not sure, but I am just trying to understand what is going on. All references I've seen so far say x should be there.  Otherwise, how did Maple determine it is dAlembert if not using the orginal form to check against?

The strange thing is calling dsolve on the ode, with no option gives different answer if calling dsolve telling it is is dAlembert:

dsolve(ode,[dAlembert]);

but

dsolve(ode)

Why it did not give the same result? 

I'd like to convert  every row of matrix to list, but failed.  I want to use batch operations map(~) not for-loop.

Download ss.mw

I noticed the following. I have 2 worksheets. A.mw and B.mw.  From A.mw, it does something as follows

libname := currentdir(), libname
foo();

Where foo() is entry inside my say TMP.mla in currentdir(). This works fine with no problems and foo() executes and complete OK.

Now I make changes to the code foo.mpl, and need to update TMP.mla. currently I use LibraryTools. But i'd like to delete TMP.mla each time and create new one so I am sure there is no problem. So from B.mw I run this code

libname:= currentdir(),libname;
FileTools:-Remove("TMP.mla");
LibraryTools:-Create("TMP.mla");
read "foo.mpl";
LibraryTools:-Save('foo',"TMP.mla");

This all works well, except it fails at the Remove line, since "TMP.mla" could not be removed, since it was open before when running the A workseet, and it seems to be still open and Maple could not delete the file.

So each time this happens, I close all worksheets, close Maple, open Maple again, and now I can run the above code OK to update the mla.

Is there a better way to do all of this?

I worry if I do not delete the mla each time, I could end up with old code there I do not want, if I rename things in my code. That is why I like to start with fresh mla file each time.  But I always have to restart Maple now to update the mla.

does maple provide a way to programatically get the name of the "current" worksheet file?

I'm looking for something analogous to
interface(worksheetdir);

which gives the directory the worksheet file is in.

thanks.

CV.mw

I need to get fine curved figure.

please suggest command.   Please also tell 6 differnt markers like symbol = asterisk.

Hello

Since my solutions are neither efficient nor concise, I wonder if someone could help me with the following problem. Suppose

L:=[[[],[],3,2,1,4],[1,4,[],5,8,[]],[5,6,7,8,[],1]]:

(Just a short and simplified version - L is a huge list). I need the elements to be rearranged as follows

newL:=[[1,5],[4,6],[3,7],[2,5,8],[1,8],[4,1]]:

that is, the first sublist of newL contains the first elements of all sublists of L without [], the second sublist of newL contains the second elements of all sublists of L without [] and so on.  

How can that be achieved without seq and remove?

Many thanks

Ed

PS. My solution 

newL:=[seq(remove(y->y=[],map(x->x[i],L)),i=1..nops(L[1]))]

The size of the sublists does not change.  

Hello everyone.

I am not really sure how to solve the following problem:

Given a parametriaztion of a surface as an interpolation in terms of given nodes as:
X(ξ,η)= Σ Νi(ξ,η) Xi, it is possible to calculate tangent and normal vectors as:
α1(ξ,η)= Σ Νi,ξ(ξ,η) Xi     α2(ξ,η)= Σ Νi,η(ξ,η) Xi  and a3(ξ,η)= cross(a1,a2) and their derivatives
α1,ξ α1,η α2,ξ α2,η etc.
For a variation of Xi i.e.  a variation of X can be calculated δX(ξ,η)= Σ Νi(ξ,η) δXi in terms of 
intermediate quantities that are as simple as  Σ Νi(ξ,η) for the position vector but get quite complicate
for the normal vector (δα3 that depends on a cross product) of given vectors  and for higher order derivatives,
or for the second variation. These variations can be also expressed with a directional derivative in the direction 
X,Y, or Z of a node i with initial position Xi.

To calculate those more complicate derivations I try to express them in terms of known less complicate ones.
Symbolizing r and s the first and second variation, and α,β firs and second derivative withh respect to ξ οr h or ξ,η.

Regarding the variation of the normal vector "a3_t" as known (i.e. a3_t,r)
and the variation of its norm "a3_n" (i.e. a3_n,r) as known too we can get the variation of
the of unit normal using the following commands:

a3 := a3_t(a, s, r)*(1/a3_n(a, s, r)): (vector-scalar operation) (1)
diff(a3, r):

the second variation
diff(a3, r):
diff(diff(a3, r), s) (2)

and even variations of its derivatives 
diff(diff(diff(a3, a), r), s): (3) 

That yield the results of the posted picture.

The problem is that if we want to calculate in the same way the variation of the derivative 
of expressions that involve the vector-vector operations i.e  variation of diff(a3_t, a)
where a3_t = CrossProduct(a1(a,r,s),a2(a,r,s)) it is not possible to do that as in (1)
we cannot substitute CrossProduct or dot product operation  with simple multiplication.

If we use the same strategy in VectorCalculus package we can get some results:
using the following commands: 

a1 := PositionVector([a1x(a, s, r), a1y(a, s, r), a1z(a, s, r)], cartesian[x, y, z])
a2 := PositionVector([a2x(a, s, r), a2y(a, s, r), a2z(a, s, r)], cartesian[x, y, z])
a3T := CrossProduct(a1, a2)
diff(a3T, r)

but then (as it is shown in the upload picture 2) the calculations are performed component-wise
are very lengthy so it is impossible to get second derivative or second derivation.

So I would like to ask is it possible to declare a1 as a vector but not give its components a1x, a1y etc explicitely but instead
declare it as a vector valued function of (a, r, s). so that it yields simpler expressions 
as "a3_t,r= a1,r(x)a2 + a1(x)a2,r".

I would also like to know if those calculations can be made simpler with and another package and if so is there an appropriate example
or a book that explains how to do that.

I would really appreciate  any idea.
Because this is a difficult problem Maple can make it very easy.

Thank you in advance.

upload1.mw

I am not geting value of F3.

question_1.mw
 

Download question_1.mw

Hello Everyone
My maple is evaluating the following provided in figure. I have  attached MAPLE file. Kindly help me to solve this. Thanks in advance.

question.mw

what is the best way to "extract" a list of terms from a sum of terms.

So something like this::

split_expr(a+b+3) should return [a,b,3]

split_expr(diff(x(t),t)) should return  [ diff(x(t),t)]

split_expr(Int(abc(t), t=2..3) + 3) should return [Int(abc(t), t=2..3) , 3]

I very often have expressions with sums of many terms, and need to run some command on each element (say simplify, or collect, etc)... i've been using convert(expr, list) to split things up, apply a command and recombine, but the convert command breaks on some cases. Maybe this is something that maple can do natively?

thanks!