## Getting Maple to re-arrange equations?...

Is there any command that will get Maple to explicitly re-arrange an equation for another variable? e.g Taking a simple example, y = x + 1 and then getting it re-arranged to x = y - 1

## Dirac function, DTFT and possible numerical integr...

Hi, I'd like to proof: int(sum(2*Pi*Dirac(w+2*Pi*k)*e^(j*w*n), k = -infinity .. infinity), w = -infinity .. infinity) = 1. Can anyone help?

## Fast dialog-less entry of equation labels...

Is there a keyboard-only way to enter equation labels that will not 'zap' the focus away to a dialog box just to enter a label? While the 'look' of the equation labels is kind of nice, I find entering them extremely annoying (zapping focus is really awful UI design).

## Plotting data from arrays...

I was hoping to get some help with a problem I've been facing for the past couple of days. Basically, I've got a quadratic which I've solved for, and found 2 complex roots, say x1 and x2, for a range of values, y. This data has since been put into an array, showing both the real and imaginary parts of the roots. The 2 roots obtained for each value of y are just the positive and negative of each other. I've then taken the data from the array, and since I'm only interested in the imaginary parts of x, I've taken the data from the array and using the seq command, obtained a list of the points x1, x2 and y I want to plot.

## How to plot functions that would be joined on one ...

How to plot functions that would be joined on one diagram? > > > How can these functions Mg_1(x), Mg_2(x), Mg_3(x), be joined in one diagram? These functions are only examples and there can be more of them (as many as the elements of the constructions). > > restart; > element A_B > > Mg_1:=x->(8/25*q*(5*l-x)^2-9/5*q*l*(5*l-x)): > Mg_1(x); > q:=1:l:=10:x1:=5*l: > plot(Mg_1(x),x=0..x1); > element B_C > q:='q':l:='l': > Mg_2:=x->(-3*q*l^2+q*l*(4*l-x)): > Mg_2(x); > q:=1:l:=10:x2:=4*l: > plot(Mg_2(x),x=0..x2); > > element C_D > q:='q':l:='l': > Mg_3:=x->(-q*l*(3*l-x)):

## dsolve(numeric) procedure; returning values other ...

I am using dsolve(numeric)with the procedure option to output the position of a body subject to acceleration. The results(position and velocity) are written into an array for the specified time-points. It all works fine. I use NLPSolve within the procedure called by dsolve as an intermediate step to calcualting the specified acceleration of the body. Is there a way to return the values calculated by NLPSolve? I can back-calculate from the output array values but it is extremely tedious. I can also view the results of NLPSolve using lprint but it is not clear how these results relate to the specified time points and I would want to store the values in a matrix.

## Solve vs. Reduce...

A friend who has Mathematica suggested to me that Maple has no equivalent to the Mathematica Reduce command. Looking at the Reduce command on the Mathematica site, it says "Reduce[expr,vars] reduces the statement expr by solving equations or inequalities for vars and eliminating quantifiers." That sounds a lot like solve( ) to me so I attempted to use Maple's solve command on the following Mathematica Reduce( ) example. Reduce[x^2+y^2<><>

## Manipulating equations; substitutions...

I am trying to enter equations from the following journal article: The link can be found in the Download 4865_Page from Lo_ApplMech_1962_V1_pp691-695.pdf
View file details Thus far I have been able to create equation (8) of the article in the attached worksheet: The link can be found in the View 4865_ring buckling.mw on MapleNet or Download 4865_ring buckling.mw
View file details

## Rand...

If possible I'd like to get anyone's opinion on the "security", (for lack of a better word), of the rand command, used to generate random numbers or integers. Lately, if you've seen some of my recent blog posts you may have noticed that I've been curious about cryptography, but I still consider myself a novice, if that. My question is, does any of the brilliant and talented people that I've met on mapleprimes think that it may be possible to "cheat" maple's random number generator ? Would it be possible by some sort of manipulation to predict this command's output with some reasonable amount of confidence ?

## unapply...

This may be a little picky but if I start a new worksheet and enter y=x^2 the return is y=x^2 and it is marked as equation (1). Then entering solve((1),y) where (1)comes from insert, label, etc., I get x^2 showing that the experession x^2 has been "applied" to y as one would expect. Next when I enter g:=unapply((1),x) the function g(x) is created using the expression x^2 and I would expect that x^2 is no longer applied to y. However, when I again enter solve((1),y) I still get x^2. So the question is, what has been "unapplied" from what, as the command (unapply)implies?

## Switching Between Input Modes In Worksheet Mode...

I'm using Maple 11, and I have a question on switching between the input modes. In the user manual it only states that one should go the 'tools' drop down menu, select the 'options' choice, and apply the 'maple input' mode to the current worksheet or globally. However, after doing this I still find myself having to click on the "text" button directly above the worksheet area to have the input text stay permanently in the red colored maple input. Is this how others also choose to permanently use the maple input in worksheets ? Is this actually the only, or correct way ? v/r,

## The return when maple can not solve it?...

If I try to solve t = 5.*x*sqrt(1.+4.*x^2)+2.500000000*arcsinh(2.*x) for x in terms of t, using solve(t = 5.*x*sqrt(1.+4.*x^2)+2.500000000*arcsinh(2.*x),x); I get a RootOf answer form. That is not very useful, so I then use allvalues(%) but it just returns the same RootOf answer. Does returning the the same RootOf answer mean that allvalues can not convert the RootOf solution into an answer that contains the roots? If so, why does solve give the root of solution when it cannot be solved? If not, what does Maple return when it cannot perform a command? I find it disturbing if Maple returns a RootOf solution if it can not solve for the roots, (if that is what is happening). It's like if I ask you what the square root of two is and your reply is that it is the square root of two. That would not be the answer to the question asked. Perhaps there is an effective way to convert the RootOf answer into one containing the roots as opposed to using allvalues(%) which doesn't do the job? Thanks for the help.

## convert to inert form?...

Given an expression is there a easy way to convert occurrencies of diff, int, limit, product, sum to their intert forms? For diff one can use convert(%,D), but for int and sum it is not the right way. Are there other ways instead of using "subs(sum=Sum,%)" etc ?