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## How to ensure that dsolve works ...

Hi i was trying to numerically integrate my freinds model with dsolve, and i am sure that I have put all the right components in the command as described in the help page, but it doesn't work. (Here is a worksheet with the model Lindas_signal_transduction_model.mw )

What is the problem with the way I have called the function?
Does anyone have a mental checklist that they use for dsolve commands? because I often struggle with making them work.

## problem using DEtools [rifsimp]...

Hello all
I'm working on calculating the conservation laws for a Gardner equation
During calculation interface problem using []

The problem is that this function only works for integer exponents

Is there another way to overcome this

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## Encrypt Procedure Question...

Hello

I found this example in the Help.

I'm wanting to export the encrypted file (the gibberish between local and end proc) to friend running another M2018, and want it to run.

I would need to rerieve "abc.mla" repository that we saved it in. But I cant find it. and if i did send it, he would be able to decrypt it surely?

Encrypt_Proc.mw

Hi,
I had written some help pages in Maple 18 that I just migrate in Maple 2018.
This seems correct except one single point: when I try ot access them from the help menu, their names are preceeded by a  "WS" label and, when I click on it, the help page appears in a new window of my Maple's session, not in the help window.
I guess "WS" means "WorkSheet" ?
How can I force the halp page of "my" function to appear in the main help page window?

(hope I was clear enough)

## How to do "simple" vector calculation (with exampl...

 I want to calculate the voltage between phase 1 and phase N in an electrical circuit:   The vectorial formula is:   Voltage drops are calculated with the current multiplied with the resistance: ΔU =   i   This is a real example with realistic values and angles. Note that i have two different vectors with the same index. This is on purpose and the vector is different. This is because the first vector is before the resistance in the wire and the one i want to find, is after the resistance in the wire (the red one).:   The negative angles is because i am using my reference which is in 0°. And are the vector to the right of my reference is the angle negative, and is it on the left of my reference is the angle negative. I dont want to explain the vectorial diagram, because i think it will do more confusion than explaining.     My question is, if the formula above is possible to solve in maple?     The result is calculated on my CAS-calulator:

The example in Maple:

## Solving two coupled PDEs which have complex pote...

I am having problems with the attached worksheet, in which I am attempting to solve a couple pair of PDEs, particularly in defining initial and boundary conditions.  See MapleExample1c.mw

Can anyone help?

Melvin

## What does VectorCalculus:-Curvature represent?...

Hi,

I'm surprised by the result of the procedure VectorCalculus:-Curvature which is always a positive scalar quantity:
For instance
c := VectorCalculus:-Curvature(<x, sin(x)>, x):
plot(c, x=0..2*Pi)
# c >=0 for all x in [0, 2*Pi]

In the help pages it's written that the (signed) curvature for a function y(x) is y''/(1+y' 2)(3/2).

y := sin(x):
c := diff(y, x\$2) / (1+diff(y,x)^2)^(3/2):
plot(c,  x=0..2*Pi)
# c < 0 if x in (0, Pi)  and  c > 0 if x in (Pi, 2*Pi)

## How to calculate the derivative of modified Bessel...

Hello,

How to calculate the derivative of modified Bessel fucntion of the first kind and order \alpha, such that \alpha>-1/2?

I need to calculate de general term of the derivative of modified Bessel function of the first kind and order \alpha.

Best regards

## shifting two orthogonal vectors in Maple...

Worm greeting to all

I use the following to plot two orthogonal vectors display(arrow(1,0), arrow(0,1)) as

Now, I need to shift these two orthogonal vectors to another point.

## How to find coordinates of the points A and B of t...

In this question at here https://tex.stackexchange.com/questions/503745/how-can-i-get-correct-the-point-a-and-b-automatically-in-this-picture/503838?noredirect=1#comment1272706_503838
The points A and B lie on the circle is intersection of the sphere x^2 + y^2 + (z-3)^2 = 25 and the plane z = 0.
How can I find coordinates of the points A and B by Maple?

## why order of coeffs not respected...

unprotect(D); f := proc (x, y) options operator, arrow; (295849/5841396)*x^2-(29441/324522)*y*x+(33995/216348)*y^2-(5989/14751)*x+(3635/4917)*y+1 end proc; 295849 2 29441 33995 2 5989 f := (x, y) -> ------- x - ------ y x + ------ y - ----- x 5841396 324522 216348 14751 3635 + ---- y + 1 4917 coeffs(f(x, y)); -5989 3635 295849 33995 -29441 1, -----, ----, -------, ------, ------ 14751 4917 5841396 216348 324522 A, B, C, D, E, F := %; -5989 295849 33995 -29441 3635 A, B, C, D, E, F := 1, -----, -------, ------, ------, ---- 14751 5841396 216348 324522 4917

## Statistical distributions accept non integer degre...

Hi,

In statistics a  "degree of freedom" is a strictly positive integer.

The three distributions ChiSquare, StudentT and FRatio from package Statistics have degrees of freedom as parameters. Nevertheless they accept any strictly positive real values for them.
(one can verify that their "Conditions" attribute is of the form [0 < n] instead of [n::posint]).

I think this ought to be corrected in future versions

## Physics package Determinant...

Hello,

I have installed the Physics Package with:

PackageTools:-Install("5137472255164416", version = 329, overwrite)

I have a question about the calculation of the Tensor determinant:

I use two ways to calculate the determinant of the same matrix:

The first with Physics package and the second with LinearAlgebra Package:

It is easy to calculate analytically the result it is : -1

But Physics Package gives : +1 and LinearAlgebra gives: -1

My question is why I found +1 with Physics Package : What I doing wrong ?.

**************************************************

restart

with(Physics)

Setup(coordinates = {X = [t, x, y, z]}, dimension = 4, metric = {(1, 1) = 1, (2, 2) = -1, (3, 3) = -1, (4, 4) = -1}, signature = +---, mathematicalnotation = true)

Define(H[mu, nu] = Matrix(4, {(1, 1) = 1+h, (1, 2) = h, (2, 2) = -1+h, (3, 3) = -1, (4, 4) = -1}, shape = symmetric))

H[]

H[determinant]

with(LinearAlgebra)

B := Matrix(4, {(1, 1) = 1+h, (1, 2) = h, (2, 2) = -1+h, (3, 3) = -1, (4, 4) = -1}, shape = symmetric)

Determinant(B)

***************************************

Sincerely yours

Xavier

## How to do simple vector addition?...

Hi

I am studying Marine Engineer, and we are gonna work alot with vectors. I am using Maple as my mathematical software and i would like to know if you can do a simple vector addition in Maple?
I have tried to make a simple vector diagram to help understand my problem.
My vector U, is my reference vector, and my two vectors I1 and I2 are the vectors i would like to plus. I know the length of both I1 and I2, and i know the angle between I1 and U and I2 and U.

If i am using my TI-nspire, i can just type in the length and angle on both I1 and I2, to my reference vector, and then plus them together. Is this possible to do in maple?

For the vectors onmy example the result of vector additon of I1+I2 = 2.42 to an angle of 48.07 degree.

The image is just for representation and is not accurate according to the lengths and angles.

Hope someone out there can help me.

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