Dear All,

 We have a long equation , we need to find a laplace transform for that eq. I found the command as ilaplace.  But its not getting executed.

 Any specific comments../ help..

regards

I'm trying to solve a system of 4 ODE's.

however I have 4 equations and six unknowns. I dont know how else to describe the functions a,b,c,d

cause these just represent vector valued functions at points (x1,y1) and (x2,y2) where i have chosing (x1,y1)=(-1,0) and (x2,y2) = (1,0)

I have that

dx1/dt = (u,v)

dx2/dt=(f,g)

I know that if i graph these functions I should get vertical lines, but I keep getting circles if I instead consider a(t) to be x(t) and b(t) to be y(t)...

I need to solve this system and plot it but i am misinterpreting something somewhere..

Hi, currently im using maple 15

the coding did work but it is not the same with the answer
here, i attach the coding with the answer

coding:
derivation := proc (A, n)
local i, j, k, t, s1, s2, m, D, sols, eqns, Andre;
eqns := {};
D := matrix(n, n);
Andre := matrix(n, n);
for i to n-1 do
for j from i+1 to n do
for m to n do
s1 := sum(A[i, j, k]*D[m, k], k = 1 .. n);
s2 := sum(A[k, j, m]*D[k, i]+A[i, k, m]*D[k, j], k = 1 .. n);
eqns := `union`(eqns, {s1 = s2})
end do end do end do;
sols := [solve(eqns)];
t := nops(sols);
for i to t do
for j to n do
for k to n do
Andre[k, j] := subs(sols[i], D[k, j])
end do end do;
print(Andre)
end do end proc

the maple result showing:

> AS1 := array(sparse, 1 .. 2, 1 .. 2, 1 .. 2, [(1, 1, 2) = 1]);

> derivation(AS1, 2);
[D11 0]
[D21 D22]

> AS2 := array(sparse, 1 .. 2, 1 .. 2, 1 .. 2, [(1, 1, 1) = 1, (1, 2, 2) = 1]);
> derivation(AS2, 2);
[0 D12]
[D21 D22]

the maple should showing

> derivation(AS1, 2);
[D11 0]
[D21 2D11]

> AS2 := array(sparse, 1 .. 2, 1 .. 2, 1 .. 2, [(1, 1, 1) = 1, (1, 2, 2) = 1]);
> derivation(AS2, 2);
[0 0]
[D21 D22]

please help., thank you

how to field plot this system?

restart;
with(Physics[Vectors]);
with(DEtools);
with(VectorCalculus);
eq2 := ...;
eq3 := ...;
eq4 := ...;
with(DynamicSystems);
sys := DiffEquation([eq2 = t, eq3 = t], inputvariable = [b(t)], outputvariable = [a(t), c(t)]);
ts := .1;
in_t := t;
sol := Simulate(sys, [in_t]);

with(DEtools):
dfieldplot([...],[a(t),b(t),c(t)],t=−2..2,a=−1..2,b=−1..2,c=−1..2,arrows=SLIM,color=black,dirfield=[10,10]);

Hello, I have a question.  I don't know why, but results of my calculations can't be saved in raschet document. This document excists, but there is no information in it! And I have an error with floating point format. How to solve that problems?

> restart;
> Digits := 5;
> NULL;
> NULL;
> NULL;
> NULL;
> NULL;
> ScS0 := P/(phi*f*kc*k0*deltad*Bm*etat);
> NULL;
> NULL;
> Sc := sqrt(ScS0);
> A := sqrt(Sc);
> B := A;
> NULL;
> mue := mu0*mur/(1+mur*dzet/lm);
> lm := 2*(LCA-A+(LC0+A))+dzet;
> NULL;
> LC0 := 3*A; LCA := .4*LC0; LD := .9*LC0;
> NULL;
> NULL;
> w1 := EE/(2*Pi*f*Bm*Sc);
> Lm := mue*w1^2*Sc/lm;
> ;
> I11 := sqrt((w2*Id/w1)^2+I0^2);
> ;
> NULL;
> ;
> h1 := sqrt(RAT*I11/deltad);
> ;
> h2 := sqrt(RAT*Id/deltad);
> NULL;
> A := .6;
> Ud := 35000;
> Id := 413;
> R := Ud^2/P;
> P := Ud*Id;
> P1 := P/eta;
> R1 := EE/I11;
> EE := 110000;
> I0 := EE/(2*Pi*f*Lm);
> w2 := w1*sqrt(P*R)/EE;
> mu0 := 4*Pi*10^(-7);
> mur := 1000;
> f := 50;
> k0 := .25;
> kc := .98;
> deltad := 0.3e7;
> Bm := 1.45;
> etat := .98;
> eta := .95;
> RAT := 1;
> dzet := 0.1e-3;
> phi := .5;
> W1 := evalf(w1);
324.55
> LLm := evalf(Lm);
13.407
> W2 := evalf(w2);
103.26
> evalf(lm);
7.2457
> evalf(LC0);
2.5877
> evalf(LCA);
1.0351
> Imax := evalf(I0);
26.117
> P1;
7
1.5215 10
> Rd := evalf(R);
84.746
> Bmm := evalf(mue*w1*I0/lm);
1.4500
> hâ := (.9*LC0*1000)/(w2+1)-4;

> evalf(hâ);

h￢
> Pred := Id/deltad;
> evalf(Pred);
0.00013767
> NULL;
> NULL;
> ll := hâ*(w2+1)+4*w2;
> NULL;
> a := am*nâ/nx;
> NULL;

> Pol := Vit*nâ;
> am := 5.1;
> am := 5.1;
> nâ := 4;
> evalf(a);
20.4
----
nx
> Vit := 35.19;
> evalf(Pol);
140.76
> plotnToka := Id/Pol;
> evalf(Id/Pol);
2.9341
> NULL;
> I1 := evalf(I11);
133.98
> NULL;
> evalf(mue);
0.0012395
> NULL;
> evalf(EE/I11);
821.02
> NULL;
> pr := "%";
"%"
> fd := fopen("C:\\Users\\Ñåìåí\\Desktop\\ÍÈÐ\\raschet4.ms", WRITE); fprintf(fd, "E=%g;Ud=%g;Imax=%g;P=%g;FR=%g;A=%g;B=%g;LC0=%g;LD=%g;LCA=%g;R=%g;BM=%g;", EE, Ud, Imax, P, f, A, B, LC0, LD, LCA, Rd, Bm); fprintf(fd, "\n %s P=%g;Id = %g;Bm=%g;I1=%g;Bmm=%g", pr, P, Id, Bm, I1, Bmm);
Error, (in fprintf) number expected for floating point format
Error, (in fprintf) number expected for floating point format
> fprintf(fd, "\n %s W1 = %g; W2 = %g; Lm=%g; Sc=%g; dzet=%g", pr, W1, W2, LLm, Sc, dzet);
Error, (in fprintf) file descriptor not in use
> fclose(fd);
Error, (in fclose) file descriptor not in use

I have a system of PDEs with 3 dependent variables (U, V, W) and 3 independent variables (x, y, t).

I need an explicit numerical solution, i.e., a table with the values of U, V and W, corresponding to several values of x, y and t.

Can anybody help me?

How can Maple solve that problem for me?

Given: a summation of one equation with its limits, equaling another summation with given limits, but NOt the equation. How do Maple be programmed to find that out? 

fx     [sum(x^(n)*y^(1-n), n=0..10, = sum(unknownequation),n=1..11)]   , find the unknown equation by maple?

Appreciating in advance,

Hi, I have defined two functions:

ex1 := (x,t,z) -> -1.132*10^(11)* exp(9.9*10^(6)*x)*exp(sqrt(-1)*(1.95*10^6*z-2.98*10^15*t))

ex2 := (x,t,z) -> -2.82*10^(12)* exp(2*10^(6)*sqrt(-1)*x)*exp(sqrt(-1)*(1.95e*10^(6)*z-2.98*10^(15)*t));

And then tried the command:

implicitplot3d( ex1, x = -10..0, t = 0..10, z = 0..10, axes = boxed, style = patchcontour, scaling = constrained, shading =z);

But the boxes are entirely blank! What is the problem here?? It should be some kind of sine curve

Maple 2016.

Why does

int(sqrt(c+d*tan(e+f*x))*(a+b*tan(e+f*x))^(5/2),x);

Causes mserver.exe to hang into a loop at full CPU and maple hangs?

Windows 7, 64 bit.  Even using timelimit() on it, it still hangs exceeding the time limit and never return. I have to kill mserver.exe or exit Maple to recover.

I have posted long time ago a patch for Shadebetween and you have transformed it into a hot fix:

http://www.mapleprimes.com/questions/205956-Error-In-Shadebetween

In the last Maple 2015 update, the problem was not fixed.

Just curious: is it fixed in Maple 2016? Because I feel that the Maplesoft team is not "impressed" by such patches.

Edit. This was a comment related to acer's patch for NLPSolve, but it was transformed (I don't know why) into a separate question.

Hello,

I am trying to find the interpolation of a 3D function.

I have the vector x, the vector y and a matrix M at my disposition.
I know how to do the pointplot3d , but I can not find the function: f(x,y) 

any suggestion?

Thank you for help

Hello

I am trying to slve the second order differential equation with initial conditions  t0=0.dy/dt=0,y0=10000

-(diff(y, t, t))-9.81+0.563e-3*(0.1832e-2*abs(diff(y, t))+0.51702e-1*abs(diff(y, t))^(3/2)+.4*(diff(y, t))^2) = 0

using 4th order runge kutta.do i need to declare a step parameter like (D(y))(t) = u or is a command that can be applied automatically?

Thanks

 rk4.mw

Hello everyone, I recently learned how to plot vector fields using maple. So far, I know of two ways using VectorField(output = plot) and fieldplot3d(some_vectorfunction). My problem is that, it seems these two functions yield slightly different plots, fieldplot3d seems to give a more accurate depiction of the actual vector field, whereas the other function gives a similar ouput but in a more 'sloppy' form. Is this normal? Or am I doing something wrong?

Here are the two plots done by each function:

fieldplot3d:

VectorField(output = plot):

Hello,

I would like to symbolically determine the rank of a jacobian matrix. In the help, I have seen that the Rank function of the LinearAlgebra can be used for this purpose. However, when I use this function, the function doesn't allow to find the different singularities that can occur on my jacobian matrix.

Here a exemple of a jacobian matrix that I obtain on a slidercrank mechanism:

The rank of this jaobian (Phi) gives 2 whatever the values of theta(t) and beta(t). However, if the values of  theta(t) and beta(t) are :theta(t)=Pi/2,beta(t)=0. The rank shouldn't be 2 but 1.

Is a way to obtain the symbolic calculation of the rank of a jacobian matrix which can distinguish different cases following the values of the parameters ? In others words, my dream will be to have a Rank function (or another algorithm) which can gives :
the rank is 2 if theta(t) different of Pi/2 [Pi] and beta(t)=0 [Pi] 
and otherwise 1 if ...
and perhaps 0 if ...

Thanks a lot for your help.

I let a piece of code with an example of calculation of the rank

RankMatrix.mw

I am trying to solve the folowing ODE with initial conditions t0=0,v0=0 and tf =80 with step 0.01 but the matrix that appears is not having the values!please help

Download runge_kutta4.mw