I am trying to duplicate the answer to a problem of the nutation of a spinning top. The problem is number 6.1.3 in the book Computer Algebra Recipes for Classical Mechanics by Richard Ens and George McGuire.

TopSC := `<,>`(5*sin(z)*exp(-(Pi-z)/(1.5)), 0, z) for z = 0..Pi

Spacecurve TopSC, when rotated about the z axis, generates the surface of revolution of the top.

The solution requires knowing the moments of inertia (MI) of the top about the z axis and the x or y axis.

Does the following integral correctly calculate the MI about the z axis?

int(2*Pi*TopSC[1]*(TopSC[1]^2), [z = 0 .. z, z = 0 .. Pi])

What sequence of Maple 2016 commands will calculate the top's MI about the x or y axis?

The following command works fine until you use it in the combination conjugate and diff.

example in Physics:

declare(phi(X));

diff(conjugate(phi(X)),x1);

phi(X) should now appear as phi with index x1 and a bar only, but

it comes as phi(X) x1 , the declare command is not effective. Non conjugate works fine.

Any idea - thanks in advance

Hi all,

need to plot the positve roots and  against so(4-->5)

restart:
assume(so,real):
m1:=5:m2:=2:m3:=1.5:a1:=0.16:a2:=0.45:a3:=0.833:d1:=0.25:d2:=0.1:d3:=0.075:
ys:=a3*d3/(m3-d3):
d:=0.5:
w3:=d*(m1-d1):w2:=d*d1*so-d*m1*so-2*a1*d*d1+a1*d*m1-a2*m1^2+a2*d1*m1+m1*m2*ys:w1:=2*a1*d*d1*so-a1*d*m1*so-a1^2*d*d1+a1*a2*d1*m1+a1*m1*m2*ys:wo:=a1^2*d*d1*so:
Q:=s->w3*s^3+w2*s^2+w1*s+wo:Q(s):
sol:=evalf(solve(Q(s),s)): S:=array([],1..3): S[1]:=sol[1];S[2]:=sol[2];S[3]:=sol[3]:

I tried to use a for loop to assign the bounds for creating an RTable in a Maple C wrapper (actually it does not matter what I do here). I checked that the for loop syntax is correct C syntax, for example even as simple as for (int i = 0; i < 2; i++){...} but the loop becomes an infinite loop and takes forever to run. Has anyone encountered the same problem as I did

Hi everybody,

For at least one function (I haven’t done extensive testing), the package Logic behaves differently in Maple 2015.0 and maple 2016.0

 
Maple 2015.0 :
Logic:-Tautology(true);
      true

Maple 2016.0
Logic:-Tautology(true);
      Error, (in sprint) integer expected for integer format   ????     (??? are mine)

For information :
1)  Logic:-Contradiction(true) retruns false for both 2015.0 and 2016.0
2) OS : Windows 7
 

Is there some modification of the “Logic” package that  I have  missed ?

Thanks in advance

 Hi everybody,

Until recently I was using Maple 2015.0 on this PC :

Windows XP
2 dual core proc Intel(R) Xeon(R) CPU E3-1225 V2 ; 3.19 GHz
64 bytes,
16 Go RAM

For two days now I am using Maple 2015.0 on this one

Windows 7
4 dual core proc Intel(R) Xeon(R) CPU 5-2637 V3 ; 3.50 GHz
64 bytes,
64 Go RAM

Comparisons of the running times for exactly the same code, consisting in 10000 independent Monte Carlo  simulations distributed over all the nodes (resp 4 and 8) give :

Windows XP :  504 sec  (with a variation of the order of  +/- 3s for different replicates)

Windows 7   :  343 sec  (with a variation of the order of  +/- 3s for different replicates)

The expected running time should be 504 * (3.2/3.5) * (4/8) = 230 s
(or 504 * (4/8) = 252 s if you neglect the acceleration due to the clock rate)
The realized running time (343 s) is thus at least  40% larger than the expected one.


Does anybody has already observed this kind of performance loss during XP -> 7 migration ?
Are there some comparisons of cpu times between Windows XP and 7 ?


Thank you all for sharing your own experience.



postscript : a NOTIONALexample of how the computations are distributed is given below

NbOfRuns := 10000:

# Data is a Matix(NbOfRuns, NbOfCols, …) constructed elsewhere

NbOfNodes := Grid:-NumNodes():
NbOfRunsPerNode := NbOfRuns / NbOfNodes:
for k from 0 to NbOfNodes do
   FirstData := 1 + k * NbOfRunsPerNode:
   LastData := (k+1) * NbOfRunsPerNode:
   Grid:-Run(k+1, MyCode, [Data[FirstData..LastData, ..], …])
end do:

I have some vector field defined on real coordinate space of 3 dimensions (R3). For example:

I want to plot this vector field in 3D (with Cartesian coordinates), but only in one z contour (for example z=0).

Can somebody help me what is the right command to do this?

Download Maple_Query_1.mw

Regards

Hi every one,

I am using Maple 7 because I am running Windows XP

I believe this equation:

> solve( 1.15=exp(-xi*Pi/(sqrt(1-xi^2))), xi);

has two solutions: xi=+0.4444364945e-1 and xi=-0.4444364945e-1

but Maple only gives -0.4444364945e-1

Why?? And how can I get the two solutions?? Thanks before hand by your comments.

I'm trying to view the source of the webpage fuelsonline.ca

I used HTTP[Get] like I did before which doesn't retrieve much of anything useful.  I thought of the sockets package which I can't seem to pull any information from.  Then I had an idea and viewed the page source which finally has information I can use if I can get Maple to read it in.  If I can get Maple to pull in the contents of the page source I should at least be able to carry it from there. 

Any ideas from anyone?

The code "solve((x+exp(-1))^x = 1, x)"gives the error "Error, (in Engine:-Dispatch) invalid subscript selector". How is this possible?

Hello people in mapleprimes,

I have an equation called aa in the following.

alias(`&delta;x`=dx, `&Delta;x`=Dx,`&Delta;y`=Dy,`&Delta;z`=Dz):
aa:=Dz=f(x+Dx,y+Dy)-f(x,y);

As for modification of this expression, I ask your favor to teach me.

Then, I want to change this aa to D[1](f)(x+theta__1*Dx,y+Dy)*Dx+D[2](f)(x,y+theta__2*Dy)*Dy.

But, to do so, I have to split aa into the one including -f(x,y+Dy)+f(x,y+Dy) between two terms

of aa.

But, as maple cancels these terms, I can't do so. How can I insert two terms, then

obtain the expression  D[1](f)(x+theta__1*Dx,y+Dy)*Dx+D[2](f)(x,y+theta__2*Dy)*Dy?

Thanks in advance.

taro

hi...how i can convert 3 couple equations to 1 equation with Placement each other?

thanks...

3-1.mw

Download 3-1.mw

I've read the help page ?printf for the format codes many times over the years. I think that this is new:

The Z modifier, "%Zm" can be used to generate an alternate equivalent dotm representation that is used in communication with the GUI and in DocumentTools related functionality for the creation of XML content for .mw files.

Could someone show me an example of that?