Hello,

I have a function, lets say g(x,y,...), that depends on many other functions. But I don´t want the results that are inside certain intervals, and I need to receive the results of those functions as something like NULL when asking for a result that is inside any of those intervals. That way, g(x,y,...) would also have to result in something like NULL if any of the lesser functions are NULL fora any given values.

I tryied using the piecewise command, and for the intervals that I wanted, it worked, but for those I wanted to be NULL, they were understood as 0, and so G(x,y,..) continued to exist but with a very different value.

To clarify what I need, I will try an exemple:

Imagine I have the function f(x)=x

I want to disconsider the results for x<2 and x>6, in a way that if I try the command 'f(1)', I will receive something like NULL and know that it is outside the range.

In the same way, I need the plot of this function f(X) to show the function only from 2 to 6, but not existing for the delimited intervals.

Ad if I continue and make g(x)=f(x)+10 , I don´t want g(x) to exist if f(x) doesn´t exist, and same for the g(x) plot, which shouldn´t be shown in the intervals where f(x) don´t exist.

Thank you very much for your atention!

Hello,

could you help me solve this error ? I don't understand what it means.

> eq3:=diff(x(t),t,t)+Gamma*diff(x(t),t)+omega[0]^2*(x(t)-(diff(x(t),t,t)+Gamma*diff(x(t),t)+omega[0]^2*x(t)+omega[0]^2*X[0])/omega[0]^2) = -omega[0]^2*X[0]:
> dsolve(eq3);
Warning, it is required that the numerator of the given ODE depends on the highest derivative. Returning NULL.

Thanks.

I remember to have seen and used a command to make the graph of the output of FeynmanDiagrams but I can not find more sample files. Someone can tell me how to do (plot a Feynman graph using the result of FeynmanDiagrams).

Thanks and sorry for my english.

Dear all,

I am trying to find the intial velocity of a ball that is shot under an angle while only the start and end coordinates are given. The air resistance should also be taken into account. 

In order to do that I have build the following Maple sheet:

Assignment_question_1.mw 

I have used two differential equations that both include the variables v0 and t, and then try to solve them. Only I receive an answer in the form of RootOf, which I cannot remove with for example allvalues. 

I have been working for quite a long time on this but I am not coming any further, so is there anyone who can find what I am doing wrong/what I should be doing else? Or maybe my whole approach is not right?

Even a small step in the right direction would be appreciated a lot!

Thanks in advance,

Elise

How do I permanently change the current directory on a MAC computer?

Kind regards

Per Kirkegaard

Hi all

The aim of following program is minimization but it is unable to produce it. where is the mistake?

Taylor2.mws

thanks a lot.

Mahmood   Dadkhah

Ph.D Candidate

Applied Mathematics Department

Not sure if this is the right place to ask this (if not, where is?)

Suppose I ask a question and get an aswer with a variable such as F=_X+5_X^2+7 and want to sort it so as to get 

5_X^2+_X+7

If I try sort(F,_X) it will read the underscore as starting a subscript... I can just highlight copy and paste an _X from the previous answer, but that is silly.

Hello,

I would like to know how to generate super/subscript characters in axis label. I have tried the double underscore (atomic variable style) and the super/subscript under "Format" in document mode but no luck at all. Any comment/suggestion is truly appreciated.

Yu-Hung Lien

Hi guys,

If I have a Hermitian 4x4 Matrix with elements that behave like complex numbers except that they do NOT commute. Is it possible to diagonalize this Matrix using Maple and the Eigenvectors - method of the LinearAlgebra package?

Cheers

NOh

P.S.: I am using Maple 18

question: solve the direction field and curve that passes through each of indicated points.use different colours.

2)dy/dx=e^(-0.01xy^2)

(a) y(-6)=0

(b) y(0)=1

(c) y(0)=-4

(d) y(8)=-4

my answer:

> restart;
> with(DEtools);
> with(plots);
> a := diff(y(x), x) = exp(-0.1e-1*x*y(x)^2);
> g := dfieldplot(a, y(x), x = -8 .. 8, y(x) = -8 .. 8, color = exp(-0.1e-1*x*y(x)^2));

> ode := diff(y(x), x) = exp(-0.1e-1*x*y(x)^2);

> ics := y(0) = 1;
> dsolve({ics, ode});
  

it doesn't solve the ics n ode. actually i don't understand at all about dsolve bcoz this relating to exponential.

please do help me.thank you

btw before this someone do help me to solve my problem with this..here comes another problem..*sigh... thank you

u[0](x)=(1/GAMMA(0.5))*int((x-tau)^(0.5-1)*(tau^2+(tau^(1.5))*(8/(3))-tau-(2)*tau^0.5),tau=0..x);

I want to find the value of this integral

thank you 

Hello everyone,

I've been trying to do some perturbation theory and ran into some problems I don't quite understand. I implemented the Hamiltonian of the Bose-Hubbard model and treated the hopping as a perturbation. Calculating the second order energy shift is easily accomplished, but when I'm only interested in one of the two occuring terms, I run into problems. The calculation takes minutes to finally fail, giving me an "too many levels of recursion"-error. I need to be able to just pick a few terms for some calculations, I'm doing, and can't figure out what I might be doing wrong. Here is the source code (download is below):

Download too_many_levels_of_recursion.mw

It would be great, if someone could point out the mistake, I'm making. I copy/pasted the last line, so there shouldn't be any typos.

Thanks in advance,

Sören

Every time I try to solve for a variable it gives me an arrow.

ex solve(5.6*10^-4=((x)(x))/(0.2-x),x)

gives me

x -> 7/62500 - 7/12500 x

How do I get it to stop giving me the x -> ?

Or at least reset some options so I don't have to reinstall the whole thing?

> with(DEtools);
> with(plots);
> a := diff(y(x), x) = e(x)^(-0.1e-1*xy^2);

> g := dfieldplot(a, y(x), x = -8 .. 8, y(x) = -8 .. 8, color = e(x)^(-0.1e-1*xy^2));
Error, (in DEtools/dfieldplot) extra unknowns found: xy

how to solve this?
>
>

Hello,In short: I try to get the eigenvalues of a 16x16 complex matrix with one variable B__z. I know, the vales are very small (~10^-24), so I multiply with 10^24 and collect B__z. Now, when I use Eigenvalues(H) [H is the matrix] the result is just wrong:

test.mw

(same with original values) - compared to Mathematica which solves and plots in about 1 sec:

Where is the problem? What should I do? Any suggestions?