## 30 Reputation

3 years, 322 days

## Varying Value until Matrix Determinant e...

Maple

Hello Everyone,

First off, thank you all for your help previously, it helped me a lot!
Today, I am struggling with another small question and I wonder if there is an easy way to do it:

I am working on a problem where I have to vary values of a 4x4 Matrix until its determinant becomes zero (and the answer to the linear equations system is no longer the trivial one...)
All values depend on a single value (kx) that I can iteratively change to get it where it needs to be.

Now I would start to write a while-loop where it would change the value according to the determinant, incl. sign changes etc.
Before I get into this, I was wondering if maybe Maple has some sort of Built-In Function that could do this for me.
(I could not find anything via the Maple Help/Google, so I thought I could ask.)

Best Regards,
Lennart

## How to create a 2nd deriative at a point...

Maple

Hello Everyone,

please forgive these kind of "easy" question, but I spent the last hour trying to figure out how to give the correct boundary conditions to my dsolve-function...
What I what is to create a function that says  where f is an arbitrary function and w is an arbitrary value. Basically, it shall create the second derivative and then evaluate it at a specific point w.
I have tried the diff-function, like this: diff(f(x),x\$2)(w) = 0, but this is outputting a mess. And I cannot get the D-operator to function with a second derivative and quite frankly I do not quite understand yet how it works.

So my question would be: How many I make Maple create a second derivative and evaluate it at a specific point?

Thank you and best Regards,
Lennart

## Enforce non-trivial solutions when using...

Maple 2017

Hello Everyone,

Firstly thank you for your help everyone with answering my other question yesterday, it really helped.
Today I present with yet another issue, which is dealing with solving differential equations using the dsolve-command.

I have written a script which is defining the differential equations, (some numbers), and the constraints. However when I let it solve using dsolve, I only get a very very trivial answer, meaning f(x) = 0.
of course this is a valid answer, but not one I can work with...
(Can I maybe give an additional information, e.g. the function type it is supposed to do this task? In the documentation there is information on setting it up as a series, but what about exponential equations?)

I have uploaded to script (very short), maybe someone knows where I went wrong?
Also, I am assuming that for solving a DE which involves a fourth order derivative I need exactly four boundary conditions, which I provided.
Things are also getting really wonky when I set Nxy to something non-zero... Then I get a solutions which involves a mysterious Z which never happened before and again all four C_x, which I assume resemble missing boundary conditions, reappear.

Any help would be fantastic! :)

Best Regards,

Lennart

 (1)

## Edit Array/Matrix directly via DataTable...

Maple 2017

Hello Everyone,

I am fairly new with Maple, but I am slowly getting the hang of it.

For a university project I need to be able to create a form where a user can input a matrix manually.
Also, I need to have something like a ComboBox where I can input how many rows that matrix will need. (1-20 or so)

I have solved the latter part by adding a "When Use"-Code that sets my Array/Matrix of the DataTable to be a Zero Matrix with the correct dimensions in accordance with the value chosen in the ComboBox.
(This is for a composite calculation, the ComboBox gives the number of plies, the matrix defines the ply orientation)

I then expected that the ZeroMatrix would serve as the baseline and the user can then manually edit the Matrix to be the correct values manually, but this gives me the error message that the DataTable cannot be edited.
I suspect the ZeroMatrix is now the "Master", because I defined it via Code.

Working with "visibleRows" did not help, because it does not change the matrix size only the size of DataTable and the user can still scroll down.

What I need is that I have a fully editable DataTable with exactly the number of rows that I specified using the ComboBox.

Does anyone of you perhaps have an idea what I could do to achieve this?
Any help would be fantastic! :)

Best Regards,
Lennart

 1 2 Page 2 of 2
﻿