Hello everybody,

I'm trying to solve two ODEs analytically but it returns this 'Warning, it is required that the numerator of the given ODE depends on the highest derivative. Returning NULL'. See the worksheet Parallel_flow.mw

Thanks.

I am not sure how/why, but here is the worksheet.

test.mw

The function evalutes fine and can be used for sequence. But it does not seem to be working with plot or Maximize.

V is assumed to between 0 and 1.

Need some help.

Thanks,

casper

Dear all,

I have to differential equations that I'd like to linearise, that is all higher order (>1) derivatives (like diff(uu[0],x$2)) and parameters (like beta^2) and the products of any derivatives with the parameters uu[0] and beta are zero (as they are assumed small).

The two equations considered are displayed below:

Up to now, I perform a very tedious substitution which is based on looking at the equations above and decide which terms I want to get rid of. Something like this, where K =1:KFBCLin:=simplify(eval(KFBC, [beta^3 = 0, beta^2 = 0,
seq(subs((diff(uu[n], x$3)) = 0),n=0..K),
seq(subs((diff(uu[n], x$2)) = 0),n=0..K),
seq(subs((diff(uu[n], t))*beta = 0),n=0..K),
seq(subs((diff(uu[n], x))^2 = 0),n=0..K),
seq(subs(g*diff(beta, x)*beta = 0),n=0..K),
seq(subs((d^2*diff(uu[n], x,t)*diff(beta,x)=0)),n=0..K),
seq(subs(-2*d*diff(uu[n], x,t)*beta*diff(beta,x)=0),n=0..K),
seq(subs((d^2*diff(uu[n], x$2,t)*beta=0)),n=0..K),
seq(subs((diff(uu[n], x)*uu[n])=0),n=0..K),
seq(subs((diff(uu[n], x)*uu[n]*beta)=0),n=0..K),
seq(subs((diff(uu[n], x)*uu[n]*d)=0),n=0..K),
seq(subs((diff(beta, x)*uu[n])=0),n=0..K),
seq(subs((diff(uu[n], x)*beta)=0),n=0..K)]));As there is a lack of automatisation, this procedure is not very helpful. Life would be easier if there was a command (or the like) that says "get rid of higher order derivatives".Any help is appreciated.Best regards,

I have purchased Maple 2015 Student Edition a few months ago.  Now, I was about to buy MapleSim Student Edition and I saw that MapleSim include a license of Maple. 

If I buy MapleSim and Maple,  I would pay 198$ even if I could have bought only MapleSim and still get both products? 

Can I get MapleSim Student without Maple at a lower price? 

Maybe the version of Maple included in MapleSim has less features and that's why the cost of MapleSim and Maple are the same? 

Thanks in advance!  

I did some search on Google and on this website, but I haven't found anything. 

Hello everyone!!

I am beggining to use Maple and i saw there are many Math Apps in the Library. I was wondering if I can see the source code of some of this Math Apps to learn how to do my own ones.

please demonstrate to me how to set up a maple document to solve a simple beam design from the scratch.

S. Hassan

I'm using commands evalDG and LieBrackets to calculate Lie Brackets of infinitisemal operators.

But how (using Maple) can i extract component from the result?

For example, I had a result:

T = (f'(x) - f(x)) D_x + D_y

I need to get its component for x - f'(x) - f(x) and y - 1.

Is there a command for this operation?

Given this

z := -d*(y+a)+a;

and say we want to replace  a-a*d by c  so that the result is  c - d*y, but this does not work:

algsubs((a-a*d)=c,z);

since Maple does not "see" the d*a expression as it is not expanded yet.  Only when writing this it works:

algsubs((a-a*d)=c,expand(z));

At first I thought since this is an "algebraic" substitution, then Maple will figure it out on its own. But it seems that the expression being substititued has to explicity show there for it to work? Looking it help, it says

"Like subs, it does not expand products or powers before substitution"

So my question is: Is the rule of thumb when using algsubs, is to always expand the expression as in the above example?

Is there another Maple command or a package, which would have found this substition on its own? (i.e. without expanding first)

with(Groebner):
T := lexdeg([x,y,z],[e1,e2]);
intermsof1 := y;
intermsof2 := -z;
GB := Basis([e1-intermsof1, e2-intermsof2], 'tord',T);
result := NormalForm(y^2-x*z, GB,'tord', T);
result := NormalForm(y^2-x*z, GB, T);

originally Basis do not have error when without parameter 'tord'

after it has argument error, it has to be added extra parameter tord

NormalForm has the same error too.

i do not understand why it has error, how to solve?

i just want to express y^2-x*z in terms of y and -z

Where is the mapleclud palltte button ?   It is not in my Maple 16,  not in   mymaplecloud

How to upload a maple work sheet into  my maplecloud private  storage ?

In Maple 2015:

restart;
with(Tolerances):
a:= 3 &+- 1;
b:= 2 &+- 1;
c:= 2 &+- 1;
solve(a*x^2+b*x+c=0,x);

gives "Error, (in evalr) improper op or subscript selector"

Is there a way to make it work with interval, i.e. Tolerances variables?  In Mathematica, the above works:

a = Interval[{2, 4}];
b = Interval[{1, 3}];
c = Interval[{1, 3}];
Solve[a*x^2 + b*x + c == 0, x]

Screen shot:

I was hoping to get similar result with Maple.  Is there differenet package/commands to work with interval variables in Maple that would support all operations if not this package?

consider quadratic equation ax^2+bx+c =0 :
the coefficients vary between -1 and +1 . just like this :
-1<a<+1 , -1<b<+1 , -1<c<+1 ;
how can some one proove that this equation should have real answers ?! can anybody help ? thanks in advance.

i am very new with Maple.

I have the following two equations:

x1=a-y1-d*y2;

x2=a-y2-d*y1;

I wish to express the first equation in terms of y1 and x2, so that

x1 = c - b*y1+d*x2;

where c=a-a*d and b=1-d^2. How can I get maple to rearrange the original equation x1 in term of y1, x2, c and b? 

This question is probably for maple devs...

I was wondering if it would be possible to outline what algorithm is used to generate replications (realizations) for various processes by the Finance:-SamplePath command (and friends). For example in the code like this:

with(Finance):

X := WienerProcess();
A := SamplePath(X(t), t = 0 .. 1, timesteps = 100, replications = 20);

Is it the Euler-Maruyama method?

Alternatively maybe you can show the portion of the code that is responsible for the integration of the SDE that the Wiener process defines.

I can't find any details related to this information in the help, and it would be very helpful to know this (and more importantly have it in the help section).

Thanks!

Hi,

     I was wondering if there is an easy way to define another set of indices in the Physics package. For example, usually greek indices are for all 4 spacetime dimensions. Using Setup(spaceindices = lowercaselatin), we can define 3 of those as space indices. I was hoping there is a more general command, so that I could use only 2 indices as "space indices". For example, X[i] would run over x,y while X[mu] would run over t, z. Is there such a command in the Physics package, or a simple way to implement this personally?

Second thing. I was playing with SumOverRepeatedIndices on an expression that contained both space indices and spacetime indices. Usually this seems to work, but in my attached example it does not. I tried the same thing with just spacetime indices in Maple 18 (newest Physics update) and it gave the same error.

Any help appreciated,

PhysicsBug.mw