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
View file details

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.   

 

need help

Hi. I have a simple problem here. I only need one result from a result list that maple gives me. As you can see below. I need the value of the variable F. But maple does not give me a single result (in this case 2), it gives me many. So how do i tell maple to give me only the first result (1.0353)? > evalf[5](solve(K = S*F^n, F));

Consider a tree that is planted at time t=0, and let V(t) denote its value at time t. The rate of interst is 100r per cent per year and is continously compounded.

a) Derive an expression for the present value of the tree.

b) The optimal time to cut down the tree is the value of t that maximise the present value of the tree. Derive the condition this optimal time must satisfy.

c) Explain what the condition means in plain language.

Consider the following model of an open economy          Y- C(Y) - X(e) = C

Question:   Consider a firm that sells in two separate markets. The inverse demand functions in the two market are  p₁= a₁-b₁.q₁    

                     and   p₂ = a₂ -b₂.q₂      and the total production   c(q) = a. (q₁+q₂)

Check that r₀ = (0, 4/3, - 5/3) is a point on the intersection of the planes  3x + y - z = 3,   x + 2y + 4z = - 4.

Hence find a parametric form for the straight line defined by intersection of these planes.

Hint: use the fact that the line must pass through r₀ and be perpendicular to the normal of each plane.

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)