I have a complicated set of first-order differential equations, which Maple seems capable of solving. So far so good. The obtained solution is fed into another complicated set of first-order differential equations, which, again, Maple seems capable of solving.

But this final (combined) solution cannot possibly be the complete one as it does not contain a specific (sub)solution which DOES satisfy both sets of equations (checked in Maple by evaluating these equations for that specific solution). And there is no warning raised concerning any solutions that may have been lost.

The problem seems to be that the integrational constants associated with solving (in turn) the two sets of equations become messed up together, or erroneously 'reused', in some mysterious way. For if I rename the integration constants of the first solution before feeding it into the second set of equations, then this specific subsolution IS contained in the final solution.

Therefore the following questions:

1.) Could there possibly be some erroneous 'reuse' of integration constants going on? It seems to me that in solving the second set of equations, PDEtools:-Solve would have to make sure that it numbers any new integration constants in such a way that there would be no conflict with the ones obtained in solving the first set of equations.

2.) Is there some (global) variable that determines what letter is assigned for the integration constants? I could use any such to easily switch names between the first and second solving.

PS: I think, it makes little sense to upload any code/worksheet here.

Hello

I am trying to plot a harmonic oscillation, but maple keeps rewriting my defintion so when I plot, it gives me a wrong graph...

How do I stop it from doing this, I am assuming it is this that causes the problem, and not the plot command?

Here is what I get:

And here is what I want - made with geogebra.

If it isn't the definition that is the problem, what plot command should I be using then?

With gratitude
Toby

Hey. I have the following Diff. Equation:

diffeq := diff(y(t),t,t,t,t)+10*diff(y(t),t,t)+169*y(t)=0

and I have the conditions y(0) = 0, y'(0) = 1, and y(t) -> 0 for t -> infinity 

I know how to do with the first two conditions, but how do you do it with a boundary? I've read the posts made earlier on here, but I can't seem to figure it out. I've tried:

dsolve({diffeq,y(0)=0,D(y)(0)=1,D(y)(infinity)=0},y(t))
 

Returns nothing.

Any help would be appreciated.

I would like to have my calculus results in its simplified form; below are some of the scenarios that can explain this.

As you can see the results are much simplified and in reduced form compared to what Maple gives. This has been tested for all integrals with roots and integrals with trigonometry functions. Is there any workaround in Maple that I would use to get it like the textbook result.

Thanks

When I resave a worksheet that is already saved on the computer desktop, it changes the position of the icon on the desktop: it is moved to the most left-upper column-row possible. Why that? Can anyone else reproduce that odd behaviour?

A worksheet can be closed using the Windows standard shortcut Ctrl-F4. But the Maple program itself cannot be closed using the Windows standard standard shortcut Alt-F4. Why that? Can anyone else reproduce that odd behaviour?

PS: I am using Maple 2017.1

This might be considered nit-picking, but nonetheless I think there is an issue: The metric tensor and its inverse are types (0,2) and (2,0) tensors, respectively. When once contracted with each other, the result is the Kronecker delta, which is then (necessarily) a tensor of type (1,1). I am therefore surprised to find that in Maple, this Kronecker delta is implemented as a type (0,2) tensor, via the command KroneckerDelta:

KroneckerDelta[mu,nu];

I don't think this makes any proper sense. I think that such an object of type (0,2) is, in fact, the metric itself. On a similar note, the (mixed tensor type) objects g_[mu,~nu] and g_[~mu,nu] are actually both Kronecker deltas, because they correspond to the metric having one index raised by contraction with the inverse metric itself. But, nonetheless, the following is the case:

g_[ mu,~nu],
g_[~mu, nu];

Relatedly, consider the following single contraction of the metric with its own inverse:

SumOverRepeatedIndices(g_[mu,nu]*g_[~nu,~sigma]);

Although this sum is formally quite correct, I think it should be given as just a Kronecker delta (of the correct mixed tensor type, that is).

Does Maple have build-in function, which when given an expression that depends on x and y, will separate it to a product of two functions, one that depedns on x only and the other that depends on y only?

The input mathematical expression is known to be seperable.

For example, If the input is

((3*y + y^2)*3*x)/(x + sin(x))

Then I'd the Maple function to take the above and return list or set of two parts  {(3*y + y^2)   ,     3*x/(x + sin(x) } (if it can't separate it, it can return null).

The API can be something as  

 f,g = find_product_functions(expression,[x,y])

Something like this is used on determining for example if RHS of first order ODE is separable in order to solve it more easily.  collect() does not really work for this. So Maple allready does this internally in its ODE solver when it checks if ODE is separable or not. But is the function available for users?

subs.mw

hi...i have a problem with subs rule

please help me.

thanks

Download subs.mw

One of the things I like in Maple is that I can return a local symbol from a proc() in some expression and it will not "conflict" with same symbol in the global space and will show the same.

I just do not know how Maple manages to do this.

For example:

foo:=proc(n)
   local x;
   x^n;
end proc;

And now if I do

x:=99;
foo(3);

Will return  x^3. This is even thought I had defined x:=99; before the call.

So there is one global `x` with value 99 and the `x` in the expression returned `x^3` did not get confused with the global `x`. Yet they look the same.

How does Maple manages to do this? In Mathematica, it always return local symbols with $nnn assigned to them to distinguish them from global symbols. (attaches the Module ID). For example, in Mathematica the same example above gives

Notice that the `x` returned from a proc() look different from inside the Module. It is not the same as the x in the global space.

Maple seems to be able to do the same thing, but using the same looking symbol. So it must be keeping track of things internally? It must know that the x in x^3 is not the same x in the x:=99 ofcourse.

Any idea how Maple does this?

With Maple 2017，when the following codes are being executed in the document mode, the error information

"Error, attempting to assign to `RealDomain:-`^`` which is protected"

will be displayed and echoed for several times, which won't appear in the previous versions of Maple.

///////////////////////////////////

restart

with(RealDomain):

with(Grid):

a := 1:

Seq(1/a, i = 1 .. 2)

///////////////////////////////////

Is this a new bug in Maple 2017?

restart;
sol:=dsolve(diff(y(x),x)= x/(sqrt(x^2-16))*1/(2*y(x)),y(x));

Gives

But the solution can also be written as

I just do not know how to transform the first solution to the second simpler one. I tried:

sol:=map(x->rhs(x),[sol]);
simplify(sol,radical);

Also tried simplify(sol,sqrt); simplify(sol,radical,symbolic); simplify(sol,size);

The simpler solution can be found as follows

restart;
sol:=dsolve(diff(y(x),x)= x/(sqrt(x^2-16))*1/(2*y(x)),y(x),'implicit');

But the term in the middle above is

Therefore the solution is really

eq:=y(x)^2-sqrt(x^2-16)-_C1 = 0;
solve(eq,y(x));

Which gives

What command to simplify the long solution to the shorter one obtained from the implicit?

The solution by Maple below is correct, but non-the-less, a little strange.

restart;
dsolve(diff(y(x),x)=3*x^2*(y(x)^2+1),y(x));

Gives

Ofcourse 3*constant is still constant. But it is a little strange and have no reason for it to be there.  When I solve it by hand

What could made Maple put the 3 in there? Again, solution is 100% correct, but it could be simpler.

Maple 2017.1

1. I have a set of equations described on different lines and I want them to be executed together and their answers to be displayed in seperate lines after that. How do I do that?
2. This is particulalry important because, at times I will have to document multiple equations sequentially and later on have their answers reffere to. This way its more structured and I can group equations falling into certain category.

Please find the attached Minimum working example. Any advise is appreciated. File link: [MWE.mw]

Thanks

Hello all, 

This is my first time with Maple, I have been a student of Mathematica for 7 years. I purchased Maple to learn a new software and I have heard great things about it. I somehow dont feel the flexibility of Mathematica in Maple documentations. It seems to be a bit constrained and not very straight forward in some aspects. Please correct me if I am wrong and also point out to tutorials or documents that I should be looking at before nose diving into Maple.

worksheet example here: 

I have faced 2 simple problems which I think is a bug in some form, or I may be wrong. Please advise.

1. How do I insert Equation 7 before Equation 6? The worksheet wont let me do it.
2. Why are 'and' and 'in' bolded automatically in SECTION format?

the following code results in an error message: Error, (in forget) lexically scoped parameter out of context

If I click on this error message, it brings me to a page which I visited too often.

if I uncomment the irrelevant minimize command, the error message disappears.

How can I prevent this error without giving irrelevant commands?

kind regards,

Harry Garst