Hi all,

I am doing some research requiring solving a system of differential equations.

Excuse me for my English, I'm Dutch)    

I have a excersice I have to make in Maple, but i don't have a clue on how to do it. I will just type it here and see what the response is.

If somebody has the Calculus book written by James Stewart, it's the "Discovery Project" on page 1040..

The figure shows the solid enclosed by three circular cylinders with the same diameter that intersect at right angles/ In this project we compute its volume and determine how its shape changes if the cylinders have different diameters.

Hi, I'm trying to find the steady states of a pair of ODEs and have used the code below but i get the message "warning, solutions may have been lost".

> restart;

> with(LinearAlgebra);

> f := (u, v) -> (u*(1-u))-a*(u*v/(v+u);

> g := (u, v) -> b*v(a(u/(v+u))-d);

> du := diff(u(t), t) = f(u(t), v(t));

> dv := diff(v(t), t) = g(u(t), v(t));

> steadystates := solve({f(u, v) = 0, g(u, v) = 0}, {v, u});

Warning, solutions may have been lost

Here is a problem that cause me trouble in Maple.  Maybe it's a careless mistake, or worst, a mathematical mistake (hope not).  Can someone can help me?

View 3867_inconsistent.mw on MapleNet or Download 3867_inconsistent.mw
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Hello,

I have some difficulties with the transfert function of a circuit. After a lot of simplification I find this equation:

R*C*diff(v(t),t)+v(t)=i(t) with R=K / i(t)

I have never seen this kind of equation before, I hope someone could help me, google is un-useful to this.
Then, I would solve this for a heavyside and sinusoidale current. How can I make a heavyside with maple ?

Thanks,
Ben

Hi!,

I've a problem with special waveforms like Square, Triangular and SawTooth. I've to solve a RLC circuit ODE for the capacitor's charge  (q(t)) as a function of time with an Voltage input of a Square Waveform, Triangular WaveForm and a SawTooth Waveform. I solved the problem with one oscillation for each waveform, but the problem says that we have to work with the periodical characteristic function for each of them.

My question : How can I transform one oscillation in a periodical function with maple? (repeating that oscillation along the time).

Why can I not get a common denominator from a/2+b/3?  Maple returns 1/2*a + 1/3*b and not (3a+2b)/6.  Normal(a/2+b/3) returns the same equation.

If I simplify(a/b+b/c) I get (a*c+b^2)/(b*c) but doesn't seem to work right with numbers in there.   

One can solve simultaneous equations if there are sufficient number of unique equations. If I do not have sufficient number of equations, I would like to generate a response that prints what is missing. How do I accomplish that? Any ideas? Thanks a lot in advance.

Trivial linear equation sample: 2x + 3y=0, y=2 - z. Solve x, y, z.

I'd like to eliminate all terms multiplied with u*Dirac(u) in a rather long function. For example, if

den:=a*u*Dirac(u)+b*u*u*Dirac(u)+c*u^(3/2)*Dirac(u)+v*Dirac(v);

is my function. Then the result I desire is,

v*Dirac(v)

I tried

subs(u*Dirac(u)=0,den);

but it did not work.

As my original function is rather cumbersome, I do not want to integrate it for this result.

Any suggestions are welcome.

Okay, I'm just starting to get the hang of Maple and I'm going through a tutorial that has a problem in it I'm having a little difficulty setting up. 

A charged disk of radius a having uniform charge density "sigma" (the actual symbol sigma) produces and electric field E_z along the z-axis given by the integral expression (I'll do the best I can to illustrate it here)

E_z(z) =  (sigma * z * int ( r/((r^2+z^2)^(3/2)) ,r=0..a))/(2*epsilon₀)

Hello all,

I would study the time response of a electronic circuit and to this I need to evaluate the laplace transform of the function :

G(I)=( 1-exp( -sqrt(I) ) ) / sqrt(I)
with I = sin(w*t)

Someone can tell me where how to do this. I have no idea.... :-(

Thanks,

Ben