Hi to everybody.  I have to manipulate a system of partial differential equation,one by one.I have in particolar to derive a lot of time my differential equations(shallow water equations),and then to group, to substitute and at the and I need time derivative in function of spatial derivative.

I'm almost done. The problem is that now every time that  I execute a command it takes  a lot of time. The entire file takes some minuts to compile. It's so slow.

Hi all,

Suppose that you want to solve x'(t)=f(x,t)   x(t0)=x0

The theory show that:

x(t+h)=x(t)+1/2*h*(F1+F2) where F1=f(x,t) and F2=f(x+F1,t+h)

SO I made procedure:

Is there a switch/case statement in Maple?  So that instead of:

if (a = a1) then

   b1

elif (a = a2) then

   b2

elif (a = a3) then

  b3

end if

Something like:

switch (a) {

case: a1 {b1}

case: a2 {b2}

case: a3 {b3}

}

???

I'm potentially going to have a long list of elif's and might need  more efficient way of doing it.

How do I plot a 3d helicoid?  I can easily plot a helix, but cannot figure out how to fill the plane to the axis, to generate the helicoid?

Leslie

I recently discovered a minor variation on the technique of building a set using a table. The purpose for using a table rather than inserting new items directly into a set is that, in a loop, the latter technique is O(n) rather than O(n).  The way I would normally do this is to assign a counter and an empty table, and then, in a loop, compute the new element, increment the counter, and insert the element into the table at the counter index.  For example,

Hi all,

while studying this ODE

Ever wondered how you can create filenames by cycle.

Well, I did, because I needed it. And I came up with something that works and because once i forgot it, I decided this time to put it here. At least, I won't forget again :) If you have a better way to do it, please, say so.

The idea:

>A:=`/home/Data/file_`; B:=`.txt`;

>for i from 1 to 3 do C:=cat(A,i,B); writedata(`C`,[i],integer);od;

Hi,

I have been trying to get a numerical solution to the following ode system for weeks. I am new to Maple, and I think my issues might be with the coding rather than the maths.

I get the error message:

Error, (in dsolve/numeric/checksing) ode system has a removable singularity at t=0. Initial data is restricted to {v(t) = 0., Phi(t) = 0.}

I know there is a singularity at t=0, so I tried setting the 'range' option to something just above 0, but it is still not working.

Hallo thar. I’m new to both Maple and programming. I’ve been searching for a Maple programming introduction online that would allow me to work on the following problem but haven’t turned up anything.  Hoping some of you can point me in the right direction.

.

I have two sets of integers {Y1,Y2..Yn} and {B1,B2…Bn}. For each value in the Y set I need to solve a function F(x) for a number of iterations given by the B value corresponding to the Y value (B1 for Y1).

Hi all,

> deq := diff(theta(t), t, t) = -g*sin(theta(t))/L;

                           2                              

So, Maple is quite helpful in that it will automatically make certain simplifications for me.  But what if I don't want it to.  For example, if I enter 2*(2+x), how do I get it to not just simply return 4+2*x?

Consider this to by end goal:

evalb(2*(2+x) = 4+2*x) => false

I have some troubles in solving a system of three trigonometric equations using the function 'solve' of Matleb.The program finds three solutions but a message of 'Warning: Warning, solutions may have been lost' also appears. Does it mean that there are other three solutions? If yes, how can I see also these three numbers?

Thanx!