i study a simple differential equations as follow and get the solution,but i faced two warning which puzzle me:

> restart;
> eq2 := diff(x(t), t) = x(t), diff(y(t), t) = x(t)^2+y(t)^2-1;
   ans1 := dsolve({eq2, x(0) = 1, y(0) = -1}, numeric, [x(t), y(t)], range = -10 .. 10)       ;

Warning, cannot evaluate the solution further left of -1.1646698, probably a singularity

Hi everyone,

I have this differential equations:

gamma1:=1;gamma2:=1;

l:=t->sqrt((x1(t)-x2(t))**2+(y1(t)-y2(t))**2);
2 2
l := t -> sqrt((x1(t) - x2(t)) + (y1(t) - y2(t)) )

DE:=[diff(x1(t),t)=(-1/(2*Pi))*gamma2*(y1(t)-y2(t))/l(t),diff(y1(t),t)=(-1/(2*Pi))*gamma1*(x1(t)-x2(t))/l(t),diff(x2(t),t)=(-1/(2*Pi))*gamma2*(y2(t)-y1(t))/l(t),diff(y2(t),t)=(-1/(2*Pi))*gamma1*(x2(t)-x1(t))/l(t)]:

I want to draw the phase portraits (x1(t...

I'm using the BoxPlot function and am trying to change the colour of two dates in the title="string" part, so they correspond with the colours of the two related box plots. Is there a way to do this?

Hi,

I have tf=0.04s but the probe plot only 0.02s at one simulation, 0.03s for another simulation ! How to oblige the probe to plot from 0s to 0.04s ?

Thanks

I have two parametric equations, one for x(t), one for y(t).  Both are ODEs of order 1.  Both are implicit.  There is no way to solve explicitly for dx/dt or dy/dt.  How can I get Maple to do a plot of the solution?  I tried DEplot but apparently it demands an explicit presentation of dx/dt and dy/dt.   I have Maple12 on a Mac, but could use Maple15 on a server.

Dear everyone,

  Hi,

  I have a simple problem of writting data into a file:

  For something like

***********

for i from 1 to 3 do
  L[i]:=i;
end do;
writedata(`d:\test.txt`,L);

***********

I got
                       ...

Hello,

Just a small question: what's the difference between writing

product( (2*i-1) mod 3 + 1, i=1..10 )

which incorrectly gives 105411381075, and writing

mul( (2*i-1) mod 3 + 1, i=1..10 )

which correctly gives 432...

And what's the reasoning behind this?

-- Regards,

Franky

Hi everyone,

While I am getting more and more comfortable with the document mode, I have some questions regarding the document block feature:

- What is a document block good for anyway?
- Why not have the whole document in one block?
- Can one join two document blocks?
- when do I "remove the document block"
- How can I make sure that say an informational 2-D math expression inside a document block never gets executed?
-- Can I still...

I have a problem related to solving the complex equation of dispersion relation.

In the plots some modes are missed. I dont know whay?

Is possible to help me? (m0^2<0).

restart;
 with(plots):
 rrr:=proc()
 local ce,c0,ve,va,cte,ct,me,m0,DT,n,EQ,i;
 ce:=6.2;c0:=0.25;ve:=5.25;ck:=1.06;ct:=0.243; cte:=2.515;
 me:=sqrt(((ce^2-v^2)*(ve^2-v^2)/((ce^2+ve^2)*(cte^2-v^2))));
 m0:=sqrt((c0^2-v^2)*(1-v^2)/((c0^2+1)*(ct^2-v^2)));

I write this code:

> e1 := a-3;
                             a - 3
> e2 := sqrt(6)*b+6;
                           (1/2)      
                          6      b + 6
> trac := e1+e2;
                                 (1/2)  
                        a + 3 + 6      b
> dter := e1*e2;
                             / (1/2)      \
                     (a - 3) \6      b + 6/
> dell := trac^2-4*dter;
                           2                           

Hello, I'm just starting to work with maple I'm working on Enzyme kinetics project and I have no idea how to solve ODE system using GEAR'S or A-stability methods. I'm looking for help.

What is wrong?

> restart;
> Digits := 10;
> dsys := {diff(E(t), t) = -kf*E(t)*S(t)+kr*ES(t)+kcat*ES(t),

Hi, I'm trying to calculate a few integrations:

E1:=map(int(N1),eta=eta0..eta2)

E2:=map(int(N2),eat=eat0..eta2)

E3:=map(int(N3),eta=eta0..eta2)

N1, N2, and N3 are 3x3 matrix are are functions of eta0, eta2. eta0 and eta2 are derived after several integration as well.

If i do not want to change the name "eta0" and "eta2", can i write something to indicate (eta0 for E1 is 8.3, eta0 for E2 is 4.5, eta0 for E3 is 7.9). I hope...

Hi,

given a ploynomial in three variables x,y,z, I want to check if it is nonnegative for all (x,y,z) in R^3.

I know there is a function 'verify' in maple but it doesn't work with my polynomial, I think it's too complex.

Do you have any idea which other function I could try?

Thank you

flower15