## MaplePrimes Questions

dear Maple Masters, i have a plotting problem about the equation |x|+|y|=5. the plot shows strange corners of the rectangle, which is absolutely incorrect as far as i'm concerned. am i wrong? or is this a bug?

## Evaluate incorrect formatted responses and prevent...

Is there a way to evaluate the format of the responses and prevent the grading? In particular I want to provide feedback to students who used a comma instead of a dot in a numerical response. At this moment Maple TA cannot deal with a correct response except for the incorrect format (0,93 instead of 0.93) and evaluates the response as incorrect. There must be a way to prevent students to grade as long as there are comma´s at places where there should be dots. Harry Garst

## how to change comma´s in dots (as a decimal sepera...

Is there a 'search and replace' method to replace all comma´s by dots (as a decimal seperator). For example 0,78 into 0.78. At this moment several students responses were graded as incorrect while the only error they made was to provide a response using a comma instead of a dot. I can export the data file and use another program to score the responses, but there may be a much more efficient method to modify the responses. Harry Garst

## Simplify expressions with Creation Annihilation op...

Hi guys, I need to simplify tedious expressions involving products of fermionic creation/annihilation operators. I loaded the Physics package, and defined the fermionic operators c[i,spin] and C[i,spin] where i=1..4, spin=1..2 My first concern is that c[i,spin].c[i,spin] doesn't return 0, while AntiCommutator(c[i,spin],c[i,spin]) does... I don't get it. Although when I apply c[i,spin].c[i,spin] to some ket it does return 0... I'm a bit lost. Any idea?

## Alternating Series - does not evaulate ... but it ...

All I have a simple Alternating Series - that will not come up with a convergent result in Maple 11. Here is the problem ... Is ... this alternating series convergent or not ? sum((-1)^n/ln(n), n = 2 .. infinity) Application of the Alternating series test says YES ... but Maple does not give a result. Thanks,
donnie
LINK to example file with Alternating Series test showing convergent test to be positive.

## Simple Infintite Series - Issue - Direct Compariso...

So I get this to calculate correctly: sum(1/n, n = 2 .. infinity); And the result is infinity - which is obviously correct. but the following does not give me a result ... sum(1/ln(n), n = 2 .. infinity); what is the trick - do i need to assume something here ? thanks, dp

## Diagnosing '"No Solutions"...

I am solving a constrained maximization problem using the Lagrangian and getting back an empty set of solutions, i.e.: solns_LSW:= How do I go about diagnosing why Maple is having difficulty finding solutions? (Once I know that, I would of course also like to know how, if possible, to change the set-up so that Maple might actually find the solution(s)!) I can see that the Lagrangian becomes non-concave for cases where lambda2>p (p is one of the variables I am solving for: there are two, s and p -- see attached worksheet). This would clearly be the case for, say, p=0 optimal (which I have reason to believe it is, based on some numerical simulations I ran).

## Simple question regarding "solve" command...

Dear all, In the attached file I try to solve expression Y for p. As Y includes dCS(p)/dp, the solve command produces an error message. I do understand that Y can't be solved for p since expression dCS(p)/dp is not fully defined. However, the result I am aiming for is simply: p = -(1/2)*(dCS(p)/dp) (with p simply being a funtion of dCS(p)/dp) Which command leads to this result? I haven't found it in the help section. Many thanks for your help! Florian View 5919_Question_solve

## Wireframe Grid resolution for 3D Plots...

Hello everyone, I was wondering if the grid resolution for "patchedcontour" wireframe 3d plots is adjustable? The only setting I know of is 'numpoints', and I can set that to a high number to get a better looking 3d plot, but this results in a dense amount of wiring for the plot. So I was curious if there is a way of getting the 'better' look for a graph while keeping the number of wires low enough so that contours are easily visible (and usable). Any takers? Thanks in advance. :o)

## Improve my code for parabolic equations...

I have been told my code is not 'perfect', I'm not too hot on maple and it has taken me a week to get to this stage. Any help or suggestions would be very welcome! h:=0.1: k:=0.001: r:=k/h^2: xl:=0: xr:=1: # left and right ends of interval in x nxpoints:=round((xr-xl)/h): ntsteps:=5: # total number of time steps iprint:=1: # print output every iprint time steps printf(cat(" x,t ","%7.3f"\$(nxpoints+1),"\n"),seq(i*h,i=0..nxpoints)): format:=cat("%7.3f"\$(nxpoints+2),"\n"): # format for printing output Boundary conditions for j to ntsteps+1 do u[0,j]:=0: u[nxpoints,j]:=0

## Summation peculiarity ... and partial fraction exp...

hello all ... peculiar problem here ... please help the expression is true that 1/n(n+1) = 1/n-1/(n+1) since 1 = n + 1 - n gives 1/n = (n+1)/n - 1 Is there a way to demonstrate this identity in Maple ? ? I cant find any trick with "expand" or such that works. This impact is also seen when evaluating ... the following ... sum(1/n-1/(n+1), n = 1 .. infinity) = 1; = print(`output redirected...`); i get the proper answer of 1 but no answer with :::

## How to compute the min and max value of a list wit...

I know maple has two functions max and min to compute the maximum and minimum of some arguments. But I have a list,such as l:=[1,2,3]; when I use the maple function min，I need to write: min(l[1],l[2],l[3]); How can I simplify the expression? If l is list with too many items,how to use min to calculate the minimum?