sorry what is what dispatch and implementing what? i get these every week for a number of cases sometimes it specifies that it is an "unhandled psi case" still waiting on that built in proc u guys where gonna dispatch like u know the reasons ppl always have a whinge about evalf not working in some cases  anyway a few people have run into these error id say.

yes its just one inbuilt function i really need to study in particular, if someone can help me to do this pls.

Hello everyone,

I have to store real-number matrixes into .mla files. Usually, I do it by using “save”, namely:

save Hi, “Hi.mla”

where i denotes is the i-th matrix I want to save. The problem is, I have to write manually :

save H1, “H1.mla” :

save H2, “H2.mla” :

…

and so on. This is not convenient as the number of matrixes to save is huge. Also, it does not work writing:

for i from 1 to n do

save H[i], “H[i].mla”

od

Any idea of what could be done? Thank you in advance.

Hi everyone,

For my first question, I am looking for some help about the following. I have the opportunity to run a worksheet in parallel on a cluster of sixteen workstations, each one endowed with twelve CPUs, through the GRID Computing Toolbox. However, I have troubles concerning how to do that.

I join the worksheet at issue: abmm_ma_1.mw The aim is to run large-scale numerical simulations of a dynamic system, depending on the values given to the initial conditions and to the parameters. The worksheet is organized in four execution groups:

1. The required packages (combinat and LinearAlgebra).
2. Calibration of the parameters and initial conditions.
3. The system, which is embedded into a procedure called SIM.
4. The activation of SIM, whose outputs are nine .mla files, each one being made of a real-number matrix.

The truth is, I do not clearly see how to modify the worksheet with some elements of the GRID package. Besides, the cluster operates under HTCondor so that running the worksheet requires beforehand the creation of a .sub file. This should be done in consistency with the aforesaid modification.

Any help is welcome, thanks a lot.

Hello,

The following problem works if i = j.   I need help to fix this problem for i ≠ j.  Thanks

A := [1, 2, 3, 4, 5];

B := [a, b, c, d];

seq([A[i], B[j]], i = 1 .. 5, j = 1 .. 4);
Error, invalid input: seq expects its 3rd argument, step, to be of type numeric, but received j = 1 .. 4

Hi guys. I am new to the Maple environment.

Was trying to do some GR calculations when the following problem arose.

restart; with(Physics);
Setup(coordinates = (X = [t, r, theta, phi]), metric = -A(r)^2*(dt^2)+B(r)^2*(dr^2)+r^2*(dtheta^2)+r^2*(sin(theta)^2)*(dphi^2));
Setup(math = true);
g_[line_element]; g_[];
Christoffel[nonzero]; Christoffel[`~mu`, alpha, beta, nonzero];
D_[mu](g_[`~alpha`, `~beta`]);
expand(D_[2](g_[`~2`, `~beta`]));
D_[2](g_[`~2`, `~2`]);

The output for the last 3 lines are:

1. 0

2. Expansion in terms of Christoffel symbols (which does equal zero on substituting various values)

3. Non-zero value.

Obviously the answer must be zero for all cases (covariant derivative of metric). So what have I missed/misunderstood here?

Regards

BuddT

What is the Maple command to simplify  -x^(a)+x^n  to zero under the assumption that a=n?

I have attempted the following command

simplify(-x^(a)+x^n) assuming a=n;

However, it did not produce zero. The following command however produces zero

subs(a=n,-x^(a)+x^n);

 How to do this operation using assumptions. How to inform Maple to assume that a=n.

Hi MaplePrimes,

I try again to ask about a procedure I wrote.  Maybee someone can spot my error.

collatz_conjecture_2.mw

Here is the broken procedure - 

cs := proc (n::integer)::integer;
local count;
description "Find the number of steps for a Collatz sequence to reach 1";
count := 1;
while 1 < n do
if `mod`(n, 2) = 0 then n := (1/2)*n else n := 3*n+1 end if;
count := count+1
end do;
return count
end proc

Regards,

Matt

im a huge fan of using the is boolean function maple has in my studies, and in as much as the CAS is a million times smarter than me, i just wanted to show an example of a situation where i am reluctant to use this feature. (see the uploaded worksheet)

perhaps someone with more  programming ability/experience than me can explain how it works, as so i can have a means of knowing whether or not it is appropriate to use in each situation.IS_function_problem_example.mw

how are iterated functions represented in maple? as in f(f(f(x))) is (x)  in conventional notation where by the reader knows it is refering to the iteration conducted 3 times on the argument x, but what does maple use to differentiate between iteration ,exponentiation and differentiation?

Hello 

can I get values from combobox?

for exemple: if I select "X" in combobox, it returns me "a:=1".

But, I'd like to put this comand inside the combobox and dont in the worksheet..

thanks a lot

Can Maple determine the value of DthetaZero such that the solution to the ODE, for some specific value of t, simultaneously provides the two values theta(t)=Pi and diff(theta(t),t)=0?

sol:=dsolve({4*sin(theta(t))*cos(theta(t))-9.8100*sin(theta(t))-(diff(theta(t), t, t)) = 0, theta(0) = 2*Pi*(1/3), D(theta)(0) = DthetaZero}, numeric)

odeplot(sol,[t,theta(t),diff(theta(t),t)],t=0..5) for trial values of DthetaZero shows that the desired value is

1.0340*Pi <DthetaZero<1.0345*Pi.

Hi 

how can I find equilibria points of nonlineay system?

Like 

x'=sin(x)+y

y'=y^2-x