## 1490 Reputation

18 years, 95 days

```--------------------------------------
Mario Lemelin```
```Maple 14.00 Win 7 64 bits
Maple 14.00 Ubuntu 10,04 64 bitsmessagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## Change of variable incomplete in DE...

Maple

Hello to you all,

I have this DE

but when I try to change the variable

I get this

>algsubs(r(t) = 1/u(t), diff(diff(r(t), t), t)-k/r(t) = -K/r(t)^2);

Why is it not done for the rest of the terms.  Is there a more easy way to do it.  Take into account that I cannot use dsolve because it is in an course in integral.

```--------------------------------------
Mario Lemelin```
```Maple 2015 Ubuntu 14.04 - 64 bitsMaple 2015 Win 10 Pro -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## A problem of conversion of units SI to F...

Maple

Hello,

In a course I am looking at, the system of units is mostly in FPS.  Wich I never use.  But they ask sometime to convert it to SI.  But with Maple, I have a problem:

For Force, it use lb that I cannot convert into N

So what unit should I use to convert FPS to SI for the force.

I know that slug*ft*s^(-2) convert to N with no problem.

```--------------------------------------
Mario Lemelin```
```Maple 2015 Ubuntu 14.04 - 64 bitsMaple 2015 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## LeviCivita function...

Maple 18

Hi,

I want to compute the determinant of a matrix A with this formula:

Can someone help me to do it.  Of course, here I am using Einstein's convention.

```--------------------------------------
Mario Lemelin```
```Maple 18 Ubuntu 14.04 LTS - 64 bitsMaple 18 Win 7 Pro -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## I have to familiarize myself with the Ph...

Maple

Hello everybody,

I will start a course in mastering QM in a MOOC format (Massive Open Online Course).  Up to now, I always do the calculation by hand and sometimes with the LinearAlgebra package.  But now I need to do the calculation more rapidly.  So I decided to learn how to use this package for this course.

The help system give a too generalized way to do it.  Even by looking the example, I didn't find praticle example to it.  So is there a generous person who could take a little bit of hi time to show me how to do it by using an exemple that yo will find attach to this post.

Besgt regards.

quantum_mechanics_DIRAC.mw

```--------------------------------------
Mario Lemelin```
```Maple 18.2 Win 7 and Ubuntu 14.04 - 64 bitsMapleSim 7 Win 7 and Ubuntu 14.04 - 64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```

## Simple code for MonteCarlo approximation...

Maple 18

Hello everybody,

But for starting easy, I try this:

with(RandomTools[MersenneTwister]);
directpi := proc (n)
local i, x, y, N;
N := 0;
Digits := 2;
for i to n do
x := GenerateFloat();
y := GenerateFloat();
if x^2+y^2 < 1 then
N := N+1:
end if:
end do:
N;
end proc;

evalf(directpi(4000)/(1000.0), 4);

3.176

I would like to know if this code is appropriate and if it is possible to have a random number between -1 to 1 so it will be easier to plot the points in the square with the circle inside.

Thank you.

```--------------------------------------
Mario Lemelin```
```Maple 18 Ubuntu 13.10 - 64 bitsMaple 18 Win 7 -  64 bits
messagerie : mario.lemelin@cgocable.ca
téléphone :  (819) 376-0987```
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