## Central Difference Method - Second & Third Derivat...

g := x -> x^3+x^2-3*x; h := 0.01; x := 1; yaydone := (g(x+h)-g(x-h))/(2*(h)); OK, I did some poking through my book, and it shows how to solve for the first derivative using the Central Difference method, it actually took me quite a while to get this formula going. This will solve for the first derivative using the Central Difference Method. I didn’t understand the book at first and thought I was supposed to use The Derivative of g(1+h) minus The Derivative of g(1-h). This really had me boggled. So now I am able to solve for the first derivative using the Central Difference Method My question is how to solve for the second & third derivative. My book has no examples for solving for anything other than the first derivative. Thanks so much for the help guys, I truly do appreciate it and I truly hate the book that I got to learn from

## module...

hi it seems that i realy did not undersand modules in maple 10 so here I come with a few question... 1, is possible to use modules right as a objects like in c++? 2, i want to have an objects: point,list where i want make list of points "pointlist:=list, pointlist.new(2,5),etc.(few points)" and i want to get list of my points related to variable poinlist.... so i need: make a new type: "point" and object "list" which can handle data of point type... how canI do this?

## Maple 6 and the mouse wheel...

My mouse wheel doesn't work with Maple 6 and Windows XP. Many of my colleaques are complaining the same. How to fix this problem?

## Row echelon form of sparse matrices...

I have a 661x662 entry matrix with <= 3 non-zero entries per row. The entries are small integers, non-zero ones being stored in a list s. I initialize the matrix by

m:=Matrix(661,662,s,storage=sparse,datatype=integer[1]);

a:=ReducedRowEchelonFrom(m);

This operation takes half an hour. Is there any way to speed it up, eg. using the NAG routines?

Thanks,
Mak

## Lagrangian density...

Dear friends Is there any way (or any package,...) that can be used to find the density of the Lagrangian of a PDE. For example the nonlinear Schrodinger (NLS) equation has the form I*Diff(u,t)+1/2*Diff(u,x\$2)-abs(u)^2*u=0. This PDE may be considered as the Euler equation which follows from the Lagrangian with density L , L=I/2*(conjugate(u)*Diff(u,t)-u*diff(conjugate(u),t))-1/2*abs(u)^2-1/2*abs(u)^4. Now, could anybody please let me know about any way to find L from NLS? many thanks sayed

## Linear Programming...

Can anyone tell me how to input the following problem in maple?
Find the maximum value of C=3x+2y on the region determined by the constraints {3x+2y<=18, 0<=x and <=4, 0<=y<=5}

Any help will be greately appreciated. Thanks in advance<code>.

## how to solve this equation?...

this is the differential equation of second derivative. because i learn Maple not long. the equation name is 'eq5' > eq5:=D(D(x1))=(a1*fx1+a2*gx1)*D(x1)+(a1*fx2+a2*gx2)*D(x2)+(a1*fxt+a2*gxt); x1(t),in the file. if you interesting ,just download the file to help me to solve this problem. regards. View 1984_diff equ.mw on MapleNet or Download 1984_diff equ.mw
View file

## How to calculate symbolic formulas including matri...

I know the power of Maple for exact symbolic and numeric computing. With Maple, we can calculate symbolic formulas expressed with scalar values such as x, y, z, and so on. For example, ``` >> solve(x+z+1=0,x); x=-z-1 ``` However, I want to calculate formulas including matrices algebraically, too. I’ll show an example of my ideal result; ``` >> solve(A*x=b,x); x=A^-1*b or x=(A^T*A)^-1*A^T*b ``` In the example above, I assume A is a matrix, and x, b are vectors. “A^-1” means the inverse of the matrix A and “A^T” means the transpose of the matrix A. I want to keep “A” as a matrix and get a result like the equation which is often written in well-known textbooks of linear algebra.

## counting rotaions...

is there a way to count the full rotations of a curve around the axis (for example a spiral) any hints in the right direction would be appreciated. thank you

## Problem with document mode...

In document mode: 1) when i start a row with (math mode): 1+2 then press ctrl+= (and Maple intert the result 3) i can't continue writing on the same row 2) when i start a row with (math mode): 1/a then press ctrl+= (and Maple intert the result 1/a) i can continue writing on the same row why? Maple 10 last patch Thank you

## plotting dirac delta with maple...

Hello I´m trying to plot the fowllowing function using maple without success: f:=t->sum(Dirac(t-k*pi),k=1..20); it seems to be syntax right. Then when I try to plot it using plot (f(t),t=-10..10); I do get an error message: Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct Error, empty plot What is happening?

## Matrix Element Summation...

Here is my Problem. Im trying to do some calculations with matrices included. Suppose I have a Matrix A and one B. I wanna create a new Matrix call it C (diagonal) like this. c_ii = sum(a_ik^2 * b_kk, k = 1 .. n) I get an errormessage sayin: "Error, bad index into Matrix" How can i force Maple to evaluate the Matrixentries first before trying to sum them up. At least I think thats the problem. I tried to pack them into a function like (i,j) -> A[i,j] which didn't work either. Thanks for your help Michael