Hello, 

I'm trying to calculate the convolution of the radiation forve in the time domain. I need to do a state space representation of a function K(t), where :

t=[0; 1; 2; 3];

k=[0.1; 0.2; 0.3; 0.4];

If you could help me with finding the appropriate command that give the matrix A, B C and D

just a remarque that in matlab used imp2ss (based on the Hankel SVD method)

thanks

Hello there, 

Is there any way to make the equation 'Given_eq_3_37a' in the calculation below to be 'desired'?

Perhaps, the issue of the 'L__1' and '1/L__1' might have been in the way, but perhaps that might be overcome in a different way. 

Thank you, 

In Kwon Park 

Download Q20201001.mw

Hi

I am trying to construct a controler for a UR5e robot, I have a simulation of the robot in maplesim and have started to look for a way to use multibody analysis to provide me with the Jacobian. However it only provieds the constraint Jacobian and as I have no position constraints on the robot, it returns nothing.

I then came across 

Link: https://www.youtube.com/watch?v=d3xJge_09E0&t=374s

However it is old and does not exactly say how to do it.

So I thought I should ask this wonderful comunity if they have an recomended way to construct the Jacobian from a maplesimmodel? I am still a beginner at maplesim and maple so any help is appreciated.

With thanks for helping me

Eric Ragnarsson

Hello everyone. I want to know how I can extract terms from a multivariate polynomial with the following 2 conditions:

1. It should have the lowest sum of the degree of x and of y; and
2. deg(x) - deg(y) should be either 0 or -1.

For instance, if I've f(x) = 100x^2y^2 + 35yx + 45x, I want an output of 35yx (not 45x; even though degree sum is 1, less than 2).

On the other hand, if I've g(x) = 13x^2y^2 + xy^2 + 2yx^2, I want an output of xy^2 (not yx^2 also).

Hello everyone, I have some weird problems with the maple. The problems are different for the document mode and the worksheet mode, however I strongly believe that they are connected. Starting with the document mode:

I simply cannot execute any command with the symbolic notation. As you can see below, I can execute basic mathematical calculations but I can't do any symbolic math. 


On the other hand, I can execute all the commands in the worksheet mode. For example check the screenshot. 
However, when I try to save that file in the worksheet mode, I get this error:

And, when I close the file and re-open again, I find all the stuff I wrote in the "math mode" disappeared 

In the worksheet below, variable x can be returned to type name after being assigned a value , but concatenated variable name A||1 cannot. Is there a way to return a concatenated variable to type name after it has been assigned a value, so it can be re-used as an unknown in solve commands?

Concatenate_Question.mw

Hello Everyone,

I have an equation system which is under-determined and thus yields infinite solutions. 
These usually come in the form of "_t1[1]" or similar variables. Mostly one, sometimes even two.
I am also working on a script for automated solving of a buckling problem and the solution yields of course these t-variables.
Everytime the code run, I get a different t-variable, which makes automation harder.

Please see attached code. (Of course simplified, not my actual code.)

It starts with a random matrix and a solution vector for the equation system.
The system is solved and its coefficients transfered to an equation.
However every time I hit "Enter" on the LinearSolve command, the name of the _t4[1] variable changes.

Is there a way to keep getting the same variable name? How do you work with this?

Best Regards,
Lennart

Download MultipleTCoefficients.mw

when i solve adomian polynomials there is a derivative withrespect to t and then put t is equal to zero. now i have to find the dervative of function with respect to t but it is already equals to zero. and i change the variable the Df could not b solved.
 

Download Adomian_Polynomials.mw

I want to create a simple symbolic transfer function from 2 vectors, lets say:        num=<a,b,c>

                                                                                                                               den=<c,b,a,d>
So my transfer function should look like this:
              H(s) = (a*s^2 + b*s + c)/(c*s^3 + b*s^2 +a*s+d)

This should be very simple but I haven't found a solution on the forums yet...

Thank you.

Is it possible to develop a code for base excitation problem where excitation data is of earthquake acceleration?

p.s. There are 12000 data available in EQ file.

Hi, I have a 1D wave equation with a piecewise initial value, I am trying to plot the solution with animation, I use the below code, However, it does not give me the animation I want but give me some error, which I am not understande.

My code is following:

pde := diff(u(x, t), t $ 2) - diff(u(x, t), x $ 2) = 0

h := piecewise(-1 <= x and x <= 0, x + 2, 0 <= x and x <= 1, 2 - x, 0)

ic := u(x, 0) = h, D[2](u)(x, 0) = 0

sol := pdsolve([pde, ic])

plots[animate](plot, [sol, x = -10 .. 10], t = 0 .. 5)

and the result is showing as picture below

There is a bug in simplify, specifically in `simplify/inert`, that prevents returning the simplified result if any of "inertfunctionnames" doesn't have a corresponding simplification procedure "inertsimplifications" (these are the names from `simplify/inert` code).
To see this, consider a simple example:

`simplify/%F`:=proc(X)
subsindets(X,'specfunc'(%F),2*`op`)
end proc:
Then we have:
A:=%F(a+b)+%G(a);
                   

simplify(A);
                       

Now, let's define a "dummy" simplification function for %G, e.g.:
`simplify/%G`:=proc(X) X end proc:

Only now do we get what we should:
forget(simplify);
simplify(A);
                     

The reason for this misbehavior seems to be simple: in `simplify/inert` any performed simplification is neglected if  "inertfunctions"<>{}. This should be corrected.

Dear Community,

Maple has the fancy VoronoiDiagram command, which generates Voronoi grids from a set of 2D distributed points. Does somebody know how the cornerpoint coordinates of the individual Voronoi cells  of the obtained Voronoi grid can be exported as a list of (x_i, y_i)  coordinate pairs? Could you possibly give a simple example?

Tx in advance, best regards

Andras

Hi, I'm solving a complicated ODEs. It is a multiple point bvp. Last time I asked a question about a similar problem(you can see https://www.mapleprimes.com/questions/230626-I-Am-Trying-To-Solve-A-Set-Of-ODEs-With). And when I use the last point 's solution to obtain the next point's solution (via approxsoln=..), it works well (it's the replicate of other people's paper). But this time I changed theoretical model, so the input parameters and the equations are some different from the previous. Some problems appears again. In the code I used a loop to calculate solutions with different lambda, but the code works on some points in front, then it appears an error "initial Newton iteration is not converging". 

Do you have some ideas to overcome it?

dsolveODEs.mw

I am getting this error when I attempt a DE plot