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Regards

Dear all

I need a help to compute the integral from -1 to 1 of product of derivative of legendre polynomial

> restart;
> with(orthopoly);

P(n, x); # Designe the legendre polynomial of degree n
I would like to compute

int(diff(P(n,x),x)*diff(P(m,x),x),x=-1..1) ;

In this previous formula when I put n=2 and m=3 I can get the result but in general  case i cannot,

Many thanks

Howdy all,

I am trying to create a solar system model by defining a force equation then using the sequence function to create a differential equation and then solving those differential equations using the initial conditions (in X,Y,Z coordinates). So far I have the code below.

Download ass4.mw

Everything works fine until I try to execute the last line. When I do that I get an error that says "Error, in dsolve/numeric/process_input. invalid specifications of initial conditions.

At this point I am not sure if the problem lies in how I have defined my initial conditions or the way i've defined the force equation but I am open to any suggestions or ideas on where I should go from here.

Thanks in advance!

Nick

i use the pdsolve to find the solutions of a system of partial differential equations,

but the result contains some indefinite integrals, how to simplify it further?

thank you

code:

eq1 := {6*(diff(_xi[t](x, t, u), u))-3*(diff(_xi[x](x, t, u), u)), 12*(diff(_xi[t](x, t, u), u, u))-6*(diff(_xi[x](x, t, u), u, u)), 2*(diff(_xi[t](x, t, u), u, u, u))-(diff(_xi[x](x, t, u), u, u, u)), diff(_eta[u](x, t, u), t)+diff(_eta[u](x, t, u), x, x, x)+(diff(_eta[u](x, t, u), x))*u, 18*(diff(_xi[t](x, t, u), x, u))+3*(diff(_eta[u](x, t, u), u, u))-9*(diff(_xi[x](x, t, u), x, u)), 6*(diff(_xi[t](x, t, u), x, x))+3*(diff(_eta[u](x, t, u), x, u))-3*(diff(_xi[x](x, t, u), x, x)), 6*(diff(_xi[t](x, t, u), x, u, u))+diff(_eta[u](x, t, u), u, u, u)-3*(diff(_xi[x](x, t, u), x, u, u)), 12*(diff(_xi[t](x, t, u), u))-6*(diff(_xi[x](x, t, u), u))+6*(diff(_xi[t](x, t, u), x, x, u))-6*(diff(_xi[t](x, t, u), u))*u+3*u*(diff(_xi[x](x, t, u), u))-3*(diff(_xi[x](x, t, u), x, x, u))+3*(diff(_eta[u](x, t, u), x, u, u)), 12*(diff(_xi[t](x, t, u), x))-6*(diff(_xi[x](x, t, u), x))+2*(diff(_xi[t](x, t, u), t))+2*(diff(_xi[t](x, t, u), x, x, x))-4*(diff(_xi[t](x, t, u), x))*u+2*(diff(_xi[x](x, t, u), x))*u+_eta[u](x, t, u)-(diff(_xi[x](x, t, u), t))+3*(diff(_eta[u](x, t, u), x, x, u))-(diff(_xi[x](x, t, u), x, x, x))};

simplify(pdsolve(eq1))

I read in the net that the method used in pdsolve numeric is the theta method, my question: is it the most efficient with regard to rate of convergence of the numerical solution of the PDE?

If not then why is it used as the default method?

Thanks.

nullspace or reducedform or Eigenvectors still can not find eigenvector in terms of  mmm , how to find this?

mmm is a variable

 in eigenvector using nullspace and eigenvector using maple function  Eigenvectors ? 

I'm reading a string from a textbox, and I need to know where the line breaks are. Hint:They are not found by searching for \n.

Dear All, 

I am using the comand " export as" form the file menu to obatain a latex version of my worksheet. The generated latex file use a package called amplestd2e.sty that should be loaded for latex compiler to function proper. Do somebody know where to find it. Thank you. N. Jand 

Hi everybody!

I am trying to find explicitely the relations between the columns of a matrix

of non-maximal rank. For example, if I have the matrix

M := Matrix([<1,2,3>, <2,4,6>, <5,6,7>]);

I would like that Maple finds that the second column is twice the first one: v_2 = 2*v_1.

How can I do?

How to reverse the order in a list?

example:

i have m := [1, 1, 0, 0, 1, 1, 1, 0]

I want to get the output like newm:=[0,1,1,1,0,0,1,1].

How to solve? Any command can help?

hi.please see attached file below and help me.thanksode.mw

Download ode.mw

if m:= [01100101, 01101100, 01100111, 01100001];

I want to get [[0,1,1,0,0,1,0,1].[0,1,1,0,1,1,0,0],[0,1,1,0,0,1,1,1],[0,1,1,0,0,0,0,1]];

Any command can solve? Thank you.

hi.please see attached file below and help me.one problem is apply differential operator on matrix and then caclute 3D integral?

maple2.mw

Download maple2.mw

Let A and B two real closed intervals.
I define b(x) as B+x for any real x ; more precisely, if B=[B1, B2], b(x) = [B1+x, B2+x]

I want to build a function f(x) such that :

1. if  A and b(x) do not overlap then f(x) = 0
2. otherwise f(x) is some expression of the covering length

For example : if A=[0, 2] and B=[-2,-1], then

1. f(x) = 0 if  -1+x < 0 or -2+x > 2
2. otherwise f(x) = L   where L is the measure of the intersection of A and b(x)

I coded a few variants using piecewise or Heaviside functions. 
In some sense I have already answered my own question ... but no one is neither elegant nor concise.

I wonder if there exist a Maple function that returns the measure of the intersection of two real intervals (when they overlap) and 0 otherwise ?