## How do i correct "error, illegal use of an object ...

HHow do i correct "error, illegal use of an object as a name"

## Singular Matrix in system of 4 ODEs...

Hello everyone,

I am trying to solve a system of 4 ODEs that describe a physical system, however, I get the message:

Error, (in dsolve/numeric/bvp) matrix is singular

Any help is much appreciated. The initial conditions are such that to find solution in steady state, that means, v(0)=v(period) and so on with all variables.

## How to solve auxiliary equation to find the famili...

Hi, I'm trying to solve auxilary equation to find its familes but I don't know what I'm doing wrong as I'm using following code:

famtemp := (diff(z(xi), xi))^2-a*z(xi)^2-b*z(xi)^3-c*z(xi)^4;

fam1 := simplify(`assuming`([dsolve(famtemp)], [b::real, a::real, c::real, -4*a*c+b^2 > 0, a > 0]))

I want to get the following family:

fam1 := 2*a*sech(sqrt(a)*xi)/(sqrt(-4*a*c+b^2)-b*sech(sqrt(a)*xi));

I hope someone will help me to solve it.

Thanks

## get term from table...

have table like table(symmetric, [() = x]) from other code not mine, strange syntax

how to extract x from table thanks

## How to eval integration under loop...

Here is my try to integrate the expression L with trapozoid or simpson

numerical_int.mw

## Code Editor Syntax and Symbolic Solutions, Weird L...

Hello Everyone,

I am currently trying to tidy up my worksheet and hide all of the script/code that I wrote in the Maple 2D-Math within the execution script of buttons etc.
Was going well so far until I started transferring code where I was using a lot of symbolic math (if I understood correctly)
There is one instance where I have a variable chi which equals x divided by a.
a being a number, e.g. 5000, while x is and remains a variable.
No problem in 2D-Math as the unknown x is dragged through all following equations.

Not so in the code editor, I think. Doing the calculation results not in x/5000, but in this:

It keeps getting worse because this term will be derived, assembled into a matrix, etc. where the expressions are getting ridiculous:

Without getting into the details of what my script should do, I believe this is a very general issue, not specific to my code.

Is the code editor / "Code when Used/Clicked" not capable of symbolic math? Oder is there some setting that could potentially help me?

Best Regards,
Lennart

## How to preserve the order when extracting the coef...

Hello (again)

I thought I won't need help with that type of question but I came across an example that says otherwise.  Here it is

```vars:=[x,y,z];

model7 := [x*(-RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)-5/4)+y*alpha[1, 2]-33/(32*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)), x*z*alpha[2, 6]+y*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561), x^2*(17*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)+17)/(alpha[1, 2]*alpha[2, 6])-17*x*y/alpha[2, 6]+2*z*x-z-(163/32+RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)^2+5*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)*(1/4))/(alpha[1, 2]*alpha[2, 6])]
```

then I issued the command

```map(w->coeffs(w,vars),model7);
```

to get

`[-33/(32*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)), -RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)-5/4, alpha[1, 2], RootOf(64*_Z^3+80*_Z^2+1104*_Z+561), alpha[2, 6], -(163/32+RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)^2+5*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)*(1/4))/(alpha[1, 2]*alpha[2, 6]), -1, (17*RootOf(64*_Z^3+80*_Z^2+1104*_Z+561)+17)/(alpha[1, 2]*alpha[2, 6]), -17/alpha[2, 6], 2]`

clearly the order does not follow model7's.

I have also tried

`[seq(coeffs(expand(model7[i]), indets(model7[i], suffixed({vars[]}))),i=1..nops(model7))];`

Is there a solution to it?

Many thanks (again)

Ed

## question about H curvature ...

Error, (in PDEtools/NumerDenom) invalid input: `PDEtools/NumerDenom` expects its 1st argument, ee, to be of type algebraic, but received {[(s_j*e^sigma*b^m*`σ_m`*y_i-s_j*e^sigma*beta*`σ_i`+s_j*e^sigma*b_ilo+(1/2)*b^(m+2)*`σ_j`*e^sigma*`σ_m`*y_i-b^2*`σ_j`*e^sigma*beta*`σ_i`+(1/2)*b^2*`σ_j`*e^sigma*b_ilo-(1/2)*b^(2*m)*`σ_m`^2*b_j*e^sigma*y_i+(1/2)*b^m*`σ_m`*b_j*e^sigma*beta*`σ_i`-(1/2)*b^m*`σ_m`*b_j*e^sigma*b_ilo+b_j*(s_ilo+(1/2)*(b^2*`σ_i`-b^m*`σ_m`*beta)*_lo)+b_j*(s_jlo+(1/2)*(b^2*`σ_j`-b^m*`σ_m`*beta)*_lo)+s_i*e^sigma*b^m*`σ_m`*y_j-s_i*e^sigma*be... when I use simplify I have this error. please guide me Saberali

## Plot two functions as one curve (3Dplot)...

Hello everyone, thank you in advance

I am trying to plot two functions in the same graph. I didn't realize how to copy the real functions here but:

At the same 3D plot

I need to use the function F1(x,xi,k,B) for values of x*xi <6  and other function F2(x,xi,k,B) for values of x*xi  >= 6

Thank you again and sorry for my rusty English.

I attached a file with these 2 functions Functions_MAPLE_PLOT_TOGETHER.mw

## How to recover only the contents of m-files? ...

Hello

I know that anames( 'user' ) recovers the contents of the workspace but I wonder whether it would be possible to recover only the contents of each m-file read within a worksheet.

Many thanks

Ed

## What is the possible reason that cause error in ds...

What is the problem with the initialconsiditions that caused this error?

"Error, (in dsolve/numeric/DAE/initial) missing initial conditions for the following: {Integer}"

Thanks.

## How do I connect to MSQL in Maple?...

I'm having trouble connecting from Maple on Windows 10 to MSQL Server. I tried Microsoft recommended drivers such as sqljdbc_6.4.0.0, did (as I thought) all required steps. The only invariable result I get is "Cannot load driver". I was wandering if anyone had implemented such a construction. Driver name & version , connection string and Java version would be greatly appreciated. Another option is to have any driver, which connects to any of standard databases (Oracle, MySQL).  The only limitation is- it must be from Windows 7 or 10.
Thanks.
A.B.

## How do I write this differential equation (Newtons...

Hi all, I would be most grateful if I could get some help with solving the tasks below using Maple.

Given the function: mx''(t)+cx'(t)+kx(t)= F_y(t)

1. Rewrite the equation above to a system of 1. order differential equations, by defining the two variables x_1(t) = x(t) and x_2(t)=x'(t) (Hint what is x'(t)?) This gives the first differential equation in the system. What is x_2'(t)?

2. Write the equations as a linear system when the outer force F_y(t) is the influence and the position x_1(t) is the answer, in other words give the system matrix A and the vectors b and r.

3. I'm given the constants m = 5kg, c = 3Ns/m and k = 20 N/m and I'm trying to find the transfer function of the system.

4. Give the systems transfer function H(s) and draw the graphs for the amplitude and phase characteristic.

Thank you!