2 years, 55 days

## correct...

I appreciate your taking the time.

Yes, I think it is correct, as if I wrote the variables wrong, I want to get the answer to equation 30 with these placements. .I very much appreciate your help

## solve equation 30 Or the same equation 9...

The first part was answered by dear friend mmcdara 4975.

But I used a simpler method to solve it, but it didn't work. Can anyone help me?

 > restart
 > eq_27 := diff(u[n](t), t\$2) = alpha*(- exp(-beta*u[n-1](t)) + 2*exp(-beta*u[n](t)) - exp(-beta*u[n+1](t)))
 (1)
 > eq_28 := n -> exp(-beta*u[n](t)) = 1+v[n](t)/alpha
 (2)
 > aux_1 := isolate(eq_28(n), u[n](t));
 (3)
 > eq_29 := eval(convert(lhs(eq_27), Diff), aux_1)          =          simplify(eval(rhs(eq_27), {seq(eq_28(n+k), k=-1..1)}));
 (4)
 > lhs_27 := eval(lhs(eq_27), u[n]=(t -> u[n](xi[n](t)))): d      := [select(has, indets(%), diff)[]]: lhs_27 := eval(lhs_27, d =~ eval(d, xi[n](t) = d__1*n + c__1*t + zeta__1)): lhs_27 := convert(eval(lhs_27, xi[n](t)=xi[n]), diff);
 (5)
 > aux_2 := select(has, indets(rhs(aux_1), function), ln)[] = H(t);
 (6)
 > eq_29_a := simplify(isolate(convert(eval(eq_29, aux_2), diff), diff(H(t), t\$2)));
 (7)
 > eq_30_1 := lhs_27=rhs(eq_29_a)
 (8)
 > eq_30 := eval(convert(eq_30_1, Diff), u[n](xi[n])=lhs(aux_2))
 (9)

 (10)

 (11)

 (12)

 > fin := simplify(subs(tanh(xi[n]) = Psi, fin1));
 (13)
 > degree(fin,Psi)
 (14)
 > FF:=convert(series(fin,Psi,7),polynom):
 > degree(%,Psi)
 (15)
 > for i from 0 to degree(FF, Psi) do     EQ[i] := simplify(coeff(FF, Psi, i)); end do
 (16)

## @mmcdara   Thank you for help...

Thank you for helping me.

## @Christian Wolinski   ok &nb...

ok

Sorry, I didn't know you

## Problem running the program!!!...

I run the attached Maple code, but no how long I wait, I can't run it. Is the code wrong?!
Maple file is word command file.

shro.mw

shrodin01.docx

## @acer   If I ask the question...

If I ask the question again here are those who see?

Because I can't run with a series of changes I make in

## That’s very kind....

I really appreciate it.

First of all, thank you for your time. If it is possible to add the file that I attached to the program, you would be very kind to me.

I desperately need this app just to get some work done. I do not intend to disturb.

## I'm so thankful...

Hi,

I'm so grateful, This was very kind of you.

You can look again at the two codes below to see what is wrong with the fsh code? (Of course if you can)

fsh.mw

## Many thanks...

Thanks for your hard work on this,

• I want to convert equation 9 to equation 12 with a series of changes and then solve it, i.e. equation 12.
• By substituting equation 4 and using equation 14 (that is, assigning the values of p_i, q_i to 1 or -1 or i and i -) and then inserting the unknown values (i.e. a_0, a_1, b_1) into equations 12 obtained, then by placing them, we get the value of the unknown function.

sh.docx

## @mmcdara  Thank you for your t...

Thank you for your time to will solve this code.

## thank you...

• This equation (Eq.9) is a differential-difference equations, (u_n are recursive relations).
• i,It is for: It is a complex equation.
• DNSE The name of the equation is: the discrete nonlinear Schrödinger equation (DNSE).
• Equation 9 is converted into an equation with a real part and an complex part, written separately, using deMoivre's formula.
• We consider that equation 4 is a hypothetical solution for equation 9.
• And m is a balance number, which here has a value of 1.

Is the explanation better now?

## Thankful...

Thankful
I want to solve the equation eq with several substitutions (substitution of the functions u , u _n +1 and u _n -1).
And after placing and simplifying, I will reach a polynomial to get the unknown values and then by placing them in the u equation, I will get the solution of the equation.

I wrote the last two commands to get the coefficients.

Can you guide me in this field.

## @mmcdara   Sorry, If the...

Sorry, If the number of equations is more, we call such devices overdeterminate and it is possible that they have a unique solution or that they do not have any solution.

## @mmcdara   Well, only these 4...

Well, only these 4 are unknown? Of course, alpha and beta can also be written?

In other words, did I make a mistake and is it practically impossible?

## Thank you very much...

Thank you very much
It is now running on version 2022.
One question, how can I get the values of a0, a1, the rest of the unknowns?
I only know the following command
Sol := solve(Eqs, {c, a[0], a[1], b[1]})
I don't know how to write here!!!

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