Is there a solve(identity ...) command for systems? I have 4 identities in the variable t.
They are Q1, Q2, Q3, Q4. I try solve(identity(Q1,Q2,Q3,Q4),t), A, B, C, D), and other forms of it, but
nothing works.
Thank you!

maplatha
 

I solved an ODE numerically. Code: question_(2).mw

delta*(M(t)*diff~(X, t$2)+C(t)*diff~(X, t))+K(t)*X=f(t)

How to calculate X(t) for different values t and to create a table like following. 

I tried to solve an equation with a A0^2*v0 + .....................= 0 with 0 as a subscripted Index. The value of A0 was 0.35.

Maple returned the result with 0.350 as a variable with subscripted 0 and no numerical result.  When changing the variable to A0 without subscripted index 0 Maple returned the numerical result correct.

Hi there!

I am trying to calculate Eigenvectors of Matrices, Maple does not seem to understand that, however. I have used the structure of the example in the "help" section

A := `<|>`(`<,>`(-1, -3, -6), `<,>`(3, 5, 6), `<,>`(-3, -3, -4));
v, e := Eigenvectors(A) 

and even the example itself, it doesn't work. Maple always responds with   

"Error, (in Matrix) triangular[] storage expects name parameters"

What can I do?

I am trying to do taylor series expansion around the critical point, but I keep getting an error, because I think Maple is taking my critical point as function {x(t) = 5, y(t) = 10}. I would like to get just the output of x(t)=  from the list of critical points. Ex. Does anyone know the maple code to get "5" and "10" from the list of critical points without typing in 5 and 10.

Hi guys;

can one please show me how to plot graphs in on layout. i want like soundalgekar2004-deka.pdf using this code

variable.mw
 

Download variable.mw

3.mw Here is my maple code that shows the animation for different values in b. The equation this is referring to is given in the code. I have done (b) and (c), and the animation is in the code, but I am not sure where for what value of b for the behavior changes, any tips on what to look for would be really helpful.

However, I am primarily concerned with (d) as I am not sure how to demonstrate periodic behaviour with dsolve. Thanks for the help!   

Hi, 
So I am trying to use Maple to find the integer points in a region(s) bounded buy a set of inequalities. But for a specific set of inequalities, in four variables,
inequalities:= [-a1-a2+a3+a4 <= 2, a1+a2 <= 3, -2*a1 <= -1, -2*a2 <= -1, -2*a3 <= -1, -2*a4 <= -1, -a1+a2+a3-a4 <= 4, -a1+a2-a3+a4 <= 4, a1-a2+a3-a4 <= 4, a1-a2-a3+a4 <= 4]; in four variables, vars :=[a1,a2,a3,a4];

I am getting the following error
Error, (in solver) invalid input: LinearMultivariateSystemInternal expects its 1st argument, eqns, to be of type ({list, set})({`<`, `<=`, `=`}), but received {a1-a2 = 0, -11/2+a1 <> 0}

Also, upon checking the inequalities by hand, I am sure that the region mentioned in the error doesnt come up. as based on the inequalities, it is not possible to have -11/2+a1 > 0. But though I could be wrong about my manual inequality analysis, the error is still suprising and worrying. 
Another point to note is that if I do a variable change, as
t1 := a1-a2;
t2 := a1+a2;
r1 := a3-a4;
r2 := a3+a4;
Then with new variables the inequalities are solved without any errors.

I am working with Maple2018 for this problem. 

Any help or insight into the root of this problem would be a lot of help. 


 

Hello! I need to solve a system of vector equations (a system with vectors, not a linear system). The coordinates of the vectors are not given. (It is a system of kinetostatic equations, I must to define reaction forces as functions of vectors of external forces.

I'm using the differential operator D to differentiate variables and look at the structure of the equations, i.e. turn things like

D[1]u-vt+v^2=0 into

D[1,2](u)-D[2](v)*t+v*D[1](t)+2*v*D[2](v)=0

However, it is assumed that this is a commutative operator, i.e. D[1,2]=D[2,1]. Can I use an option to have it not commute, or should I look into using the DETools package?

Thanks,

Mike

with(Physics);
Setup(mathematicalnotation = true):
Setup(dimension = 3, coordinates = (X = [x, y, t]), metric = -ut^2*(dx^2)+ut^2*(dy^2)+(-ux^2-uy^2+1)*(dt^2)+2*ux*ut*dx*dt+2*uy*ut*dy*dt):
              ut := Physics:-diff(u(X), t)
ux := diff(u(x, y, t), x);
                  ux := Physics:-diff(u(X), x)
uy := diff(u(x, y, t), y);
                  uy := Physics:-diff(u(X), y)
Define(S[mu, nu] = 1/(d-2)*(Ricci[mu, nu]-1/(2*d-2)*Ricci[`~alpha`, alpha]*g_[mu, nu]));
             Defined objects with tensor properties
Define(C[mu, nu, rho] = D_[nu](S[rho, mu])-D_[rho](S[nu, mu]));
             Defined objects with tensor properties
g_[];
Physics:-g_[mu, nu] = 

 
C[mu, nu, rho, nonzero];
          [Length of output exceeds limit of 1000000]
utt := diff(u(x, y, t), t, t);
               utt := Physics:-diff(u(X), t $ 2)
uxx := diff(u(x, y, t), x, x);
               uxx := Physics:-diff(u(X), x $ 2)
uyy := diff(u(x, y, t), y, y);
               uyy := Physics:-diff(u(X), y $ 2)
uxt := diff(u(x, y, t), x, t);
                uxt := Physics:-diff(u(X), t, x)
uyt := diff(u(x, y, t), y, t);
                uyt := Physics:-diff(u(X), t, y)
utt = ut*ut*(1/(-ux^2-uy^2+1))*(uxx+uyy)-2*ut*(1/(-ux^2-uy^2+1))*(ux*uxt+uy*uyt);
Basically here the cotton tensor exceeds the output limit in maple, however I am supposed to be showing how the cotton tensor vanishes, the last part of the code is me trying to input a relation of u_tt to various other derivatives of u in the hope that the cotton tensor can be simplified from this equation but nothing has changed as a result, can anyone help me? 

restart;
PDE := diff(y(x,t), x,x,x,x)+(diff(y(x, t), t,t))=0;  
# Initial/boundary conditions 
  BCs:=y(0,t) = 0, y(1,t) = 0,D[1](y)(0,t)=0,D[1](y)(1,t)=0;

  ICs:=y(x,0) =0, D[2](y)(x,0)=1 ;
  num_solution := pdsolve(PDE, {BCs,ICs}, numeric); 
  num_solution :-plot3d(x=0..1, t=0..1);

1st Question:How to plot the 2D at point x=0.5?

2nd Question: How to use PDEplot?

How to use a Lyapunov function to prove the stability of a system of differential equations and then check the stability? My initial thoughts were to use a contour plot?

I havev to calculate the intersection of three planes and need to plot them, when I try to plot them I get this error:

Error, (in plot3d) bad range arguments: (Vector(3, {(1) = -4*_t2[3], (2) = 3*_t2[3], (3) = _t2[3]})) = -8 .. 8, y = -20 .. 20

This is my code so far:

with(LinearAlgebra);
A := <1, 1, -2|3, 4, -7|-5, -8, 13>
b := <0,0,0>

x := LinearSolve(A, b)
P1 := x+3*y;
P2 := x+4*y;
P3 := -2*x-7*y;
plot3d([P1, P2, P3], x = -8 .. 8, y = -20 .. 20, plotlist = true, color = [blue, red, green]);
Error, (in plot3d) bad range arguments: (Vector(3, {(1) = -4*_t2[3], (2) = 3*_t2[3], (3) = _t2[3]})) = -8 .. 8, y = -20 .. 20

Hello,

I will buy some books for improving Maple.

Especially, I'm looking for the good books with Maple code for solving differential equations (Analytical and numerical solutions for Both Ordinary and Partial Differential equations).

Book Language: English.

Best regards.