Hello!

I have a system of ODEs which I can solve numericaly with Maple. What I try to do (still without success) is to compute the i-th derivatives of the solutions at a certain point of the interval. For example (a mini-version):

eq_0 := D(x[0])(t)=(-2*x[0](t))/(1-x[1](t));

eq_1 := D(x[1])(t)=(2*x[0](t))/(1-x[1](t));

sys := {eq_0, eq_1, x[0](0)=1, x[1](0)=0};

fcns := {x[0](t), x[1](t)};

p:=dsolve( sys, fcns, numeric, method=classical[rk2], output=listprocedure );

(OK, this is very easy, but it is only an example.)

Now I want to compute the 6-th derivative of x[0](t) at t=1/2. The analytic form can be obtained if D(x[0]) is differentiated 5 times and x[0] and x[1] are substituted by their numerical solution. I have read about differantiating in Maple, but I still cannot get this work.

Hi -- I want to check the sign of a polynomial. Here's the polynomial expression
(1/16)*(9*s^5-3*s^4*m-34*s^4*pa+12*s^3*m*pa+46*s^3*pa^2-18*s^2*m*pa^2-24*s^2*pa^3
+12*s*m*pa^3+s*pa^4-3*m*pa^4+2*pa^5-16*s^4+64*s^3*pa
-96*s^2*pa^2+64*s*pa^3-16*pa^4+16*p^2*s+48*p^2*m-64*p^2*pa)/(s-pa)^4
and here's the parameterization: pa>s and pa>m.
Generally checking the sign of the polynomial involves checking the signs of the factors...so, I'd like to factor the above expression. I haven't worked with "factor" much in Maple. Applying it as just factor(expr) with expr equal to the above expression does nothing. So not sure the best approach.

Hello again Maple experts,
I have four nonstochastic variables s11, s12,s21,s22.. from there I have 2 random variables X1 and X2 (to begin, it may be a uniform distribution U[-1,1]) . I generate the random variables y1 and y2:
y1 = min(s11+X1, s21+X2)
y2 = min(s12+X1, s22+X2)
1. How could I obtain with MAPLE the distribution of
Z= (y1)^(1/2)+log((40-y2)*(80+2*y2-3y1))?
2. And how could I obtain the expected value of Z?
Thanks in advance for any help.
Regards,
Jean

I have a nested list, say
test:=[[1,2,3,4],[5,6],[7,8,9]]:
and I want to use something like
map(x->1/x,test);
to get
[[1, 1/2, 1/3, 1/4], [1/5, 1/6], [1/7, 1/8, 1/9]]
but it won't work...
map doesn't go in nested lists and it rather returns
[1/[1, 2, 3, 4], 1/[5, 6], 1/[7, 8, 9]]
I can't find an example about this simple problem,
I'm sure it must be easy though but I'm losing my mind on this one.

Hi, I have been trying to use Euler's method to calculate approximate values on maple 11, and I cannot get it to work. Can someone show me the exact things to enter? I am given y', an initial value, and step size. I looked it up online and followed various directions, but still haven't been able to get an answer.

Assuming that I have the following
row1 = a, b, c
row2 = a, b, c
row3 = b, c , a
I would like to obtain for each column the frequencies:
column1 a: 2, b: 1, c:0
column2 a:0, b:2, c: 1
column3 a:1, b:0, c:2
How could I do it with maple?
Do I need to use some package?
Thanks in advance,
Jean

Hi,
I am trying to evaluate a number of N[i,j] variables and part of the process of finding them includes "Int" and afterwards "evalf". In case I calculate them manually as in (functions, variables and constants previously defined):
G11 := diff(psi2, a[1], a[1]);
dpsi2 := diff(psir2, a[1], a[1])+diff(psiz2, a[1], a[1]);
Izr := -E*(Int(u*G11, [z = -infinity .. infinity, r = 0 .. infinity]))+Int(u*((j*g0+j^2/r^2+(1/4)*g0^2*r^2-2/rho)*G11+dpsi2), [z = -infinity .. infinity, r = 0 .. infinity]):
Izr2 := evalf(Izr);
N[1,1] := (a[1]*a[1])*Izr2;
I obtain neat results for Izr2 and N[1,1] (i.e. the integration is done and results in a number).

I updated my blog entry - for those who might be interested:

me, blogging
Suppose I've plotted 3 functions:

plot(f(x),x=0..1);

plot(g(z),z=0..1);

plot(h(w),w=0..1);

Now I'd like to have these 3 plots following one after another (in a successive manner) in 1 plot like diagram. How can I perform such a task?

Another question:

How can I have a plot in reverse range? For example instead of plot(x^2,x=0..1), I'd like to have sth as plot(x^2,x=1..0), i.e. the horizontal range begins from 1 and ends to zero (also the vertical range is from (1)^2=1 to (0)^2=0).

Why does Maple take (much) more time on calculating than Mathematica? For example, some time ago, I calculate this integration: int((sin(x)/x)^100,x=-infinity..infinity); although Maple is able to give the correct answer, but it takes about 5 minutes to achieve this answer. However, when I did the same thing in Mathematica, the time spent on calculating is less than one minute. Why is there such a notable distinction between the two computer algebra systems?
PS: Versions of the two softwares that I use are Maple 11 and Mathematica 6.

Hi everyone.
Does anyone know how to derivate such function:

piecewise(t
and avoid in result: Float(undefined) in points where function is not continuous. You can see what I'm writing about in file

trajectory I appended.
The problem is that I have a big simulation of constrained robot and I need to derivate my equations which are not continuous and I cannot change it.
Thanks for any help.
Piotr
P.S. I forgot to write I use MAPLE version 8

Hello everyone,
I have a problem with Maple 11, and I was wondering if anyone can provide insight.
When I create a function, say:
r := t-> [t^2, 2t, 3t^3];
And then somewhere further down my document I do...
r(2);
or perhaps..
plot3d(r(t), t=0..1);
Etc... there are times where it appears that maple 'forgets' what my functions are and I'm forced to click on my initial function definition and press Enter again to 'remind' maple what 'r' is. I don't understand why this happens... if I say x=2 in a programming language, it stays =2 until I redefine it otherwise, but with maple my functions don't remain what I define them to be and I don't understand why my functions simply don't 'stick'???

Hey folks.
I was wondering if there is anyone fairly well versed in the modular linear algebra package who can help me figure out how to solve a problem.
I am doing some research about some coding theory, and I find myself needing to row reduce a matrix with entries from the integers modulo 2.
I am using Maple 11 on a Mac, and have read the help file on the RowReduce command in the LinearAlgebra[Modular] package, which explains all of the parameters I need to include. I thought I understood the parameters, but I get an error each time I try to do use the command. The error I get states that the matrix is singular, which shouldn't be a problem since I am not trying to invert anything.

How do I get the ln's in ln(2*x-2*a)/a-ln(2*x)/a to combine? How do I get maple to convert exponentials into hyperbolics and back? In general, is there a good reference for collect, combine, convert, simplify, expand, factor and all similar functions? How to massage an expression into the form you want seems to be an enormous and/or hit or miss affair. Thanks.

How Do I Do Conditional Probability with Maple?
I use Maple 10 Retail Student.
My word problem is "Should You Switch". What I want to know is how Do I use Maple to a) compute it and verify my work b) Use Maple for this.
You are a contestant on a game show where a million dollars is hidden between on of three closed doors. You geuss door 1 BUT before opening that door the game show host opens door 2 and shows you that nothing is hidden there. He offers you the chance to switch your geuss to door 3. Should you switch?
How do I use Maple to verify my work?