How do I remove infinity from a list

s:=[f(x) , exp(a), GAMMA(2x)-1 , infinity , 1, -infinity]

remove(has,%,infinity)

does not work.

It should yield

s:=[f(x) , exp(a), GAMMA(2x)-1 , 1]

In the second case RegSubs treats the expression m as containing special characters. Can one tell it to treat what it receives as a literal string - perhaps some "escape" function?
 

Download regsubs_problem.mw

How to solve the following second order ODE system? (I want to solve analytically and numerically and to compare the results) Thanks. Best regards.

where

Initial conditions:

Other symbols in the equation (v_0,a_0 etc.) are constant.

MY CODE TRY:  Code.mw

I tried to write a code for matrices in the question. ( I used x instead of gamma in the code)

restart:
n:=2:
  M:= tau -> Matrix
      ( n,
        n,
        shape=identity
      )
      +Matrix
      ( n,
        n,             (i,j)->2*x*sin(i*Pi*v_0*tau)*sin(j*Pi*v_0*tau)
            ):
  C:=tau -> Matrix
              ( n,
                n,
                (i,j)->4*(i*Pi*v_0*tau)*sin(i*Pi*v_0*tau)*cos(j*Pi*v_0*tau)
              ):
  K:=tau -> n^4*Pi^2* Matrix
      ( n,
        n,
        shape=identity
      )-Matrix
      ( n,
        n,
        (i,j)-> 2*mu*(i*Pi*v_0)^2*sin(i*Pi*v_0*tau)*sin(j*Pi*v_0*tau)+2*mu*(i*Pi*a_0)*sin(i*Pi*v_0*tau)*cos(j*Pi*v_0*tau)
      ):
f:=tau -> Vector
      ( n,
        (i,j)-> x*Pi^2*(Pi/2+v_0^2*sum(((1-(-1)^k)/k^3)*sin(k*Pi*v_0*tau),k=1..infinity)-a_0*sum(((1-(-1)^k)/k^4)*cos(k*Pi*v_0*tau),k=1..infinity))*sin(i*Pi*v_0*tau)
      ):
      
 
X:= Vector(n, i-> x[i](t)): 
sys:= M(tau).diff~(X, tau$2)+C(tau).diff~(X, tau)+K(tau).X=f(tau):

how I can determined time period?

thank you

period.mw
 

Download period.mw

For some reason algsub or applyrule is not performing what they has to do.

I dont understand exactly where the below lines are wrongly declared. Clearly the variable is not substituted

Can this expression be transferred to gamma function form?

Int(exp(-Pr*(s*eta*lambda^2+lambda*eta+exp(-lambda*eta))/lambda^2), eta)

How can we solve the following pde by Maple? 

where v is velocity, v with dot is acceleration. (So, I think we will assume that acceleration is fixed.) And \delta is Dirac distribution.  E,I,m, M , g are fixed numbers.

Boundary conditions are:

Initial conditions are:

You can find the equation in the code: question.mw

Hi,

this "sum(1/(1+x)^t, t=1..infinity)" is (in my opionon) one of the most standard infinity summation and has the closed form 1/x. 
i used maple 18 and it was executed and i got the closed form 1/x.

with maple 2018 i get the non executed form, also the same inert form as "Sum(1/(1+x)^t, t=1..infinity)".

if i try "sum(1/(1+2)^t, t=1..infinity)" i get 1/2 as result.

why does the version above not working? any ideas?

thank you.

Dear friends,

I'm trying to solve a linear system of PDEs. After applying the casesplit command Maple returns: 

diff(U, z, y, x, x) = 0; diff(G, y,y,z) = diff(U,x,y,z);  diff(G,x,y,z) = diff(U,x,x,z)     

(with U(x,y,z), G(x,y,z)) 

The solution to the first equation is U = F4(x, y)+ F3(x, z) + F2(y, z) + x*F1(y, z). 

However, given this solution, I cannot satisfy diff(G,x,y,z) = diff(U,x,x,z).  What could I be doing wrong? 

Many thanks for your help.  

Hi

I have a problem with my maple. 

corrupt file 

Is there anybody who can help me solve this problem. 

Casper 

This may seem a bit trivial, but I prefer f'(x) to writing diff(f(x),x) in 1D input. How to achieve?

differential.mw

Download differential.mw

Hello,

Simple question:

Why does

restart;

(exp(I*t))^q;

`assuming`([simplify(%)], [t > 0, t < 2*Pi, q > 0, q < 1])

not simplify to exp(I*t*q)

?