I want to simplify an expression via simplify();

However since the expression is very long (length(expression)=2713899) Maple is taking too long...So far one hour.

I have already simplified several expressions of a similar kind with lengths of up to 400.000 which worked fine within minutes.

Is there any way to speed up the process. Am I making a mistake?

Thanks in advance

of a square matrix having its entries 1,2,...16? See http://oeis.org/A085000 for info.

I want to plot this contour 4x^2+9y^2=160  onto the same f(x,y)=4x^2+9y^2.  The error I keep getting is

Error, (in plot3d) first argument must be either in standard or parametric form

Thanks

Hi all,

I think the developers should pay attention to this problem.

This simple expression with Threads:-Map executed perfectly on my machine with 8-threaded CPU and 16 GB RAM:

Threads:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

But the similar expression with Grid:-Map never be executed:

Grid:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

Maple or freezed, or crashed every time. Although the consuming of memory is not reached even 50%.

The similar problem exist for Grid:-Seq too. With `$`(1 .. 3*10^6) Grid:-Map and Grid:-Seq executed normally. With `$`(1 .. 5*10^6) - 50/50. But not with `$`(1 .. 10^7).

Is this a real bug of Grid:-Map and Grid:-Seq ?

Or is exist a way to fix this problem?

Thanks.

Updated:

I got a new error behavior of Grid:-Map in this case instead crash or freeze:

Grid:-Launch(numnodes = 8);

st := time[real](); Grid:-Map(proc (i) options operator, arrow; ln(i)/2. end proc, [`$`(1 .. 10^7)]);

time[real]()-st;

print(`output redirected...`); # input placeholder

`System error, `, "bad id"
2267.482

I hope this helps developers to fix this bug.

I can;t seem to get DSOLVE working.  Will some kindly soul please send me a complete example, starting with an f(x) & clearly documented?   Many thanks.

AB

Suppose I have a file, test.txt, which the content is

2
2 0.0 0.0 0.0
1 0.0 0.0 1.6

I would like to save 

Z:=2;

C[1,1]:=2;C[2,1]:=0.0;C[3,1]:=0.0;C[4,1]:=0.0;

C[1,2]:=1;C[2,2]:=0.0;C[3,2]:=0.0;C[4,2]:=1.6;

However, if I use readdata("...",4), seems it do not work.

Is there any flexible command in maple can readfile with different column? Thank you very much!

Hello,

On my multibody model, I meet a mistake during the simulation which is the following :

"Constraint projection failure at 10s".

1) Do you have a idea on this error message so as to correct the settings for the simulation?

2) I would like to know more about the projection method. If, I'm not wrong, there is not a lot of documentation about the projection method used in Maplesim. 

   a) Does someone have some references (scientific papers) which present the theory used for the projection method in Maplesim?

   b) In ths sense, I would be very interesting about learning the theory of the projection method in order to be able to tune correctly the following options linked to the projection method :

- Projection Iterations
- Projection Tolerance
- Event Projection
- Event Iterations
- Event Hysteresis

Thanks a lot for your help.

Hello,

Is it possible to define the orientation of a body with a matrix transformation ?

I have seen this option for the fixed frame but not for the rigid bodies.

I would like to define the rigid bodies thanks to transformation matrix so as to make some checking.

Thank you for your help.

Hello,

In my mechanism, I use absolute coordinates.

For the rotation (namely the initial angles/ angular velocites), I didn't see the difference between Inboard and Euler.

It seems to me that in the two cases, the initial angles are defined with regard to the inertial frame and for both, different kind of rotations can be defined.

Have you some ideas on these two options ?

Thank you for your help.

I am having difficulty with the contourplot3d.  When I hit enter it comes back with a blank plot.  Either Im doing somthing wrong or my machine can't handle it.

Hi,

The system below is successfully solved by using rfk45_dae method

I want to write the Runge Kutta scheme according to rfk45 method so as to have

S'=F(x,U,S,..), U'=G(x,U,S,..), ...

The presence of diff(S,x,x) in the second equation doesn't help me to definie F and G functions.

Thanks for your help 

restart;

with(plots);

Eq1 := diff(f(eta), eta, eta, eta)+f(eta)*(diff(f(eta), eta, eta))-(diff(f(eta), eta))^2-M^2*(diff(f(eta), eta))+B(f(eta)*(diff(f(eta), eta, eta))*(diff(f(eta), eta))-f(eta)^2*(diff(f(eta), eta, eta, eta))) = 0;

Eq2 := (diff(theta(eta), eta, eta))/Pr+f(eta)*(diff(theta(eta), eta))-2*(diff(f(eta), eta))*theta(eta) = 0;

Pr := 1

M := 1

S := 0

epsilon := 1

blt := 10

bcs1 := f(0) = S, (D(f))(0) = epsilon, (D(f))(blt) = 0;

bcs2 := theta(0) = 1, theta(blt) = 0;

L := [0, .2, .4, .6, .8, 1.2];

for k to 6 do R := dsolve(eval({Eq1, Eq2, bcs1, bcs2}, B = L[k]), [f(eta), theta(eta)], numeric, output = listprocedure); X1 || k := rhs(R[3]); X2 || k := rhs(R[4]); Y1 || k := rhs(R[5]); Y2 || k := -rhs(R[6]) end do:

print([(X2 || (1 .. 6))(0)])

Consider the equation

eqn1:=5^(2*abs(y-1)+2) = (1/15625)*625^abs(y-1);

and note that

eval( eqn1, y=-3);
eval( eqn1, y=5);

both return valid solutions. So why does

testeq(eqn1);

throw a numeric exception.

Given the manual description of testeq(), I would expect it to return either true or FAIL - but not a numeric exceprion!!!!

Any ideas?

Hi there,

I've created some nice 3D-plots. I want to export them and insert them in LaTex. Exporting to EPS gives me a zero-byte-file but no printable data.

I've already read that I'm not the first to have this issue and there is obviously a work-around by enabling the Classic-Worksheet-mode. Unfortanely this mode appears to be not available in Maple 17 under MAC OSX. 

Is there another way to solve the problem?
Would help me a lot.

Thanks!