Maple Questions and Posts

These are Posts and Questions associated with the product, Maple
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.

The Vim editor ships with a maple.vim file, which is a "maple mode". It was first created by Charles Campbell, and I provided some updates (up to Maple 9.5). I am about to rev that up to Maple 11, so I would like to know if there are any feature requests which I should consider rolling-in at the same time? If you have little bits of vim scripts which you yourself use, by all means, send them along! [You'll get full credit for that, I am fine with being just an aggregator...

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).

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).

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?
Dear all! In the attached document X is a function in p and F. Solving X for F returns three possible solutions in p. When I put p=6 all three solutions contain complex numbers. However, when I put p=6 at the very top of the file, transforming X into a function of only F, Maple finds two possible solutions for F both without complex numbers (11.1 and 3371.9, whereas 11.1 is the "right one"). How come that Maple doesn't yield the same results when I define p=6 later in the file? I'd be very greatful for any suggestions and help! Best regards, Florian
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