## Why does (-8)^(1/3) become 1+Complex(1)* (3)^(1/2)...

Hello people in mapleprimes,

I have a question about why what is shown by maple by simplify(-8)^(1/3) is 1+ Complex(1)* (3)^(1/2)?

Solutions of x^3=-8 are -2, 1+Complex(1)*(3)^(1/2) and 1- Complex(1)*(3)^(1/2). And, as for the last one, 1- Complex(1)*(3)^(1/2), it is

the conjugate of the second, so it might not need to be written, because of it being easily seen so.

Is it the same reason why just -2 is not shown as the result of simplify((-8)^(1/3))?

PS. I know the instruction to use surd in such a case.

the reason I asked this question is this:

I am reading Essential Maple, where

ln(z) = ln(rho*exp(Complex(1)*theta));

ln(rho*exp(Complex(1)*theta))=ln(rho)+Complex(1)*theta;

ln(rho)+Complex(1)*theta;=ln(rho)+Complex(1)*arctan(y,x);

and

z^a=exp(a*ln(z));

and

"Because of

exp(w*Pi*Complex(1)*k)=cos(2*Pi*k) + Complex(1)*sin(2*Pi*k);

and

cos(2*Pi*k) + Complex(1)*sin(2*Pi*k)=1;

we could equally well have chosen

ln_k z = ln(z) + 2*Pi*Complex(1)*k"

are written.

Supposing these, there is a sentence that

"we choose k=0, and thus -Pi<=theta<=Pi to be the one (that for our canonical logarithm).

Every computer algebra language and numerical language follows this standard and takes the

complex logarithm to have its imaginary part in this range.

With this definition, (-8)^(1/3)=1 + Complex(1)*sqrt(3), and not -2. (the end of quotation)"

And, I can't understand the last sentence"With this definition", so I asked the above question.

I hope someone give an answer to the above question.

taro

## Comparisons

Maple

Hello all ,

Having read a recent post about comparing Maple and Mathematica I'd like to throw my 2 cents (FWIW).

It is *silly* (not to say stupid) to compare these two softwares.

Maple can do "things" that Mathematica can't. For examples Differential Geometry, Lie Algrebra, covariant derivative and the like.

And Mathematica Manipulate command is far better than Maple Explore (just another exemple).

I have being using Maple since Release V.2 (1992) and Mathematica since Release 1.1.a (1991).

I use both of them on a daily basis and I *LOVE* them both.

Inputs are welcome :-)

Kind regards to all,

Jean-Michel.

## differences between professional and personal Mapl...

Could someone explain what are the main (functional) differences between professional and personal Maple editions for 2845\$ and 299\$ respectively?

Tx, Andras

## How to write a recursive function with two variabl...

Dear All,

I am new to maple and trying to write a recursive function with two input variables, but when i execute the statement it shows error "Error, (in B) too many levels of recursion"

Following is the set of instructions which i am trying to execute:

if n=1 then

B(m,n):=omega(m);

else

B(m,n):=sum(omega(j)*B(m-j,n-1),j=1..m-1)

end if

After execution, i try to access B(1,1) or B(2,1), the following error occurs

B(1, 1);
Error, (in B) too many levels of recursion

I'll be grateful, if someone can help me to fix this problem.

## Eigenvalues are not calculated ...

I created my own package and one procudure inside this package is to calculate the eigenvalues of a identity matrix, as shown below

Then, I use this package in another document, all other procedures work well except the procedure calculating egigenvalues, as shown below

How to solve this problem? Thank you.

## Error in ImportMatrix ...

Ok so I managed to get my data into a google spreadsheet by using a google app script (JavaScript in the cloud).
The data is updated daily. I now want to access it from Maple. Axel has helped me write the following
procedure to do just that for (https websites and not just http):

theDLL := "C:\\WINDOWS\\SYSTEM32\\urlmon.dll";

FileTools:-MakeDirectory("C:\\mydir");
myDirectory := "C:\\mydir";
myFile := "data1.csv";
Destination := cat(myDirectory, "\\", myFile);

ImportMatrix("C:\\mydir\\data1.csv", source = csv)
end proc;

return DL(), FileTools:-RemoveDirectory("C:\\mydir", recurse = true, forceremove = true)

end proc:

However now I get an error message saying:

Error, (in ImportMatrix) no delimiter found after line 768, column 2

Any ideas how to solve this?

## Alternatives of Java to display interactive Maple ...

Dear Maple users

Sometimes I would like to place certain Maple content on my website, for example making it possible for the user to rotate 3d objects (created in Maple) directly on the webpage, in the browser. I did that on one of my own webpages, written in Danish though:

http://www.matematiksider.dk/soapbubbles.html

If you scroll to the Catenoid shape, almost at the bottom of the page, one should be able to click this object to have a Javaapplett started. I made this years ago with the help of the great tools created by Konrad Polthier:

http://www.javaview.de/maple/index.html

It wasn't easy, but I made it work. Things have changed since that time, however. Java is more and more "in bad standing". I was blocked when I tried opening it because of security. Banks is looking for alternatives, also because of security. And the mostly used browser now, Chrome, has stopped supporting it.

Now my question: Is there an alternative? Will HTML5 make it possible to make some kind of "Maple plugin" for Interactive Maple objects to be placed on webpages and interacted with in a Webbrowsers?

Erik

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

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 bits
Maple 2015 Win 7 - 64 bits messagerie : mario.lemelin@cgocable.ca téléphone :  (819) 376-0987

## Best source for learning maple ...

What is the best source of learning maple for an abecedarian to become a professional?

## IVP Dsolve Error...

Hello,

I am a student doing some self study over the summer trying to work through some of the John Taylor computer problems from his classcial mechanics book. Currently I hit a snag that most likely comes from the fact I am not well acquinted with Maple for solving IVP and DE's (we used Matlab in my DE class). I just need to know how I remove the following error:

Error, (in dsolve/numeric/SC/IVPsetup) initial conditions must be numeric

Here is a copy of my code:

R := 5;
5
g := 9.8;
9.8
deq1 := {diff(x(t), [`\$`(t, 2)]) = -g*sin(x(t))/R, x(0) = 20};
/ d / d \ \
{ --- |--- x(t)| = -1.960000000 sin(x(t)), x(0) = 20 }
\ dt \ dt / /
dsol1 := dsolve(deq1, numeric);
Error, (in dsolve/numeric/SC/IVPsetup) initial conditions must be numeric

My hunch is that I need to set x'(0)=0 or something like I do not have enough intial values to solve the problem, but I could be wrong. Anyway anyone who can point out my mistake feel free to do so! Thank you!

## too small numbers...

In my calculations, I encounter with too small numbers, e.g. 0.4e-10. My question is that how can I make the maple to ignore these small numbers and considers them as zero and not to incorporate them into subsequent calculations???

## How to change stacklimit in OpenMaple?...

when using jopenmaple, some maple command will cause jvm crash due to stack overflow exception, but has no trouble if issued in Maple GUI.

after some digging, i found that the stacklimit in Maple GUI is 130941. but if I use jopenmaple to invoke command "kernelopts(stacklimit);", the result is 893.  further more, if i try to increase stacklimit by issuing "kernelopts(stacklimit=894)", maple kenerl tells me that i cant increase it beyond hardlimit.

so here are my questions:

1. why are the two stacklimits different?

2. is there a way to increase the hardlimit so that i can increase the stacklimit when using java invoking maple commands?

some platform information:

OS: windows 7 64bit

JAVA: jdk1.7 64bit

thanks.

## How do I change the 2D and 3D plot scale in Maple ...

I have started to use Maple 18 and I have found that my scale starts at 2.*10^16 for all functions I graph no matter if its 3D or 2D. Is there a way to change this scale?

## conditional ODE. simplest Stick-slip problem...

Hi,

sorry for that question, i'm a beginner in maple but i think my question is not as simple.

So, i want to solve numerically this first equation :

but the second term is present only if k*(U*t-x)>μc*m*g  (stick-slip problem)

initial conditions : U=1m/s; x=0m; k=10 for example

My problem is simple, i don't know how to use conditional statement for such an ode in maple.

I've tried > Xr := U*t-x;
> k := 10; m := 1; g := 10; mu := .2;
> if k*Xr > mu*m*g then ode1 := m*(diff(x(t), t, t)) = k.Xr-mu*m*g else ode1 := m*(diff(x(t), t, t)) = k.Xr end if;

But, of course, too optimistic.

Thank to anyone who will solve that (isuppose) simple problem

Philippe

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