Question: Seeking Insights into a Novel Approach for Factoring?

I’ve spent considerable effort trying to understand how the solution was derived, particularly the approach involving the factoring of G′/G. Despite my attempts, the methodology remains elusive. It seems there’s an innovative idea at play here—something beyond the techniques we’ve applied in similar problems before. While I suspect it involves a novel perspective, I can’t quite pinpoint what it might be.

If anyone has insights into how this factoring is achieved or can shed light on the underlying idea, I’d greatly appreciate your help.


 

restart

with(PDEtools)

with(LinearAlgebra)

with(Physics)

with(SolveTools)

undeclare(prime)

`There is no more prime differentiation variable; all derivatives will be displayed as indexed functions`

(1)

_local(gamma)

Warning, A new binding for the name `gamma` has been created. The global instance of this name is still accessible using the :- prefix, :-`gamma`.  See ?protect for details.

 

declare(Omega(x, t)); declare(U(xi)); declare(u(x, y, z, t)); declare(Q(xi)); declare(V(xi))

Omega(x, t)*`will now be displayed as`*Omega

 

U(xi)*`will now be displayed as`*U

 

u(x, y, z, t)*`will now be displayed as`*u

 

Q(xi)*`will now be displayed as`*Q

 

V(xi)*`will now be displayed as`*V

(2)

``

ode := (-V*a[2]+a[1])*(diff(diff(U(xi), xi), xi))+U(xi)*(((-gamma+sigma)*k+b)*U(xi)^2-a[1]*k^2+(w*a[2]-alpha)*k-w) = 0

(-V*a[2]+a[1])*(diff(diff(U(xi), xi), xi))+U(xi)*(((-gamma+sigma)*k+b)*U(xi)^2-a[1]*k^2+(w*a[2]-alpha)*k-w) = 0

(3)

F := sum(c[i]*(m+(diff(G(xi), xi))/G(xi))^i, i = -1 .. 1)

c[-1]/(m+(diff(G(xi), xi))/G(xi))+c[0]+c[1]*(m+(diff(G(xi), xi))/G(xi))

(4)

D1 := diff(F, xi)

-c[-1]*((diff(diff(G(xi), xi), xi))/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*((diff(diff(G(xi), xi), xi))/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)

(5)

S := diff(G(xi), `$`(xi, 2)) = -(2*m*mu+lambda)*(diff(G(xi), xi))-mu

diff(diff(G(xi), xi), xi) = -(2*m*mu+lambda)*(diff(G(xi), xi))-mu

(6)

E1 := subs(S, D1)

-c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)

(7)

D2 := diff(E1, xi)

2*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)*((diff(diff(G(xi), xi), xi))/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)/(m+(diff(G(xi), xi))/G(xi))^3-c[-1]*(-(2*m*mu+lambda)*(diff(diff(G(xi), xi), xi))/G(xi)-(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2-2*(diff(G(xi), xi))*(diff(diff(G(xi), xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*(-(2*m*mu+lambda)*(diff(diff(G(xi), xi), xi))/G(xi)-(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2-2*(diff(G(xi), xi))*(diff(diff(G(xi), xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)

(8)

E2 := subs(S, D2)

2*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)^2/(m+(diff(G(xi), xi))/G(xi))^3-c[-1]*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)

(9)

D3 := diff(E2, xi)

-6*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)^2*((diff(diff(G(xi), xi), xi))/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)/(m+(diff(G(xi), xi))/G(xi))^4+4*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)*(-(2*m*mu+lambda)*(diff(diff(G(xi), xi), xi))/G(xi)-(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2-2*(diff(G(xi), xi))*(diff(diff(G(xi), xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)/(m+(diff(G(xi), xi))/G(xi))^3+2*c[-1]*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)*((diff(diff(G(xi), xi), xi))/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)/(m+(diff(G(xi), xi))/G(xi))^3-c[-1]*((2*m*mu+lambda)^2*(diff(diff(G(xi), xi), xi))/G(xi)+(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+3*(2*m*mu+lambda)*(diff(diff(G(xi), xi), xi))*(diff(G(xi), xi))/G(xi)^2+6*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))^2/G(xi)^3-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(diff(G(xi), xi), xi))/G(xi)^2+6*(diff(G(xi), xi))^2*(diff(diff(G(xi), xi), xi))/G(xi)^3-6*(diff(G(xi), xi))^4/G(xi)^4)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*((2*m*mu+lambda)^2*(diff(diff(G(xi), xi), xi))/G(xi)+(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+3*(2*m*mu+lambda)*(diff(diff(G(xi), xi), xi))*(diff(G(xi), xi))/G(xi)^2+6*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))^2/G(xi)^3-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(diff(G(xi), xi), xi))/G(xi)^2+6*(diff(G(xi), xi))^2*(diff(diff(G(xi), xi), xi))/G(xi)^3-6*(diff(G(xi), xi))^4/G(xi)^4)

(10)

E3 := subs(S, D3)

-6*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)^3/(m+(diff(G(xi), xi))/G(xi))^4+6*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)/(m+(diff(G(xi), xi))/G(xi))^3-c[-1]*((2*m*mu+lambda)^2*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)+4*(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+12*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))^2/G(xi)^3-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)^2/G(xi)^2-6*(diff(G(xi), xi))^4/G(xi)^4)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*((2*m*mu+lambda)^2*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)+4*(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+12*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))^2/G(xi)^3-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)^2/G(xi)^2-6*(diff(G(xi), xi))^4/G(xi)^4)

(11)

``

NULL

K := U(xi) = F

K1 := diff(U(xi), xi) = E1

K2 := diff(U(xi), `$`(xi, 2)) = E2

K3 := diff(U(xi), `$`(xi, 3)) = E3

``

L := eval(ode, {K, K1, K2, K3})

(-V*a[2]+a[1])*(2*c[-1]*((-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-(diff(G(xi), xi))^2/G(xi)^2)^2/(m+(diff(G(xi), xi))/G(xi))^3-c[-1]*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3)/(m+(diff(G(xi), xi))/G(xi))^2+c[1]*(-(2*m*mu+lambda)*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)/G(xi)-3*(-(2*m*mu+lambda)*(diff(G(xi), xi))-mu)*(diff(G(xi), xi))/G(xi)^2+2*(diff(G(xi), xi))^3/G(xi)^3))+(c[-1]/(m+(diff(G(xi), xi))/G(xi))+c[0]+c[1]*(m+(diff(G(xi), xi))/G(xi)))*(((-gamma+sigma)*k+b)*(c[-1]/(m+(diff(G(xi), xi))/G(xi))+c[0]+c[1]*(m+(diff(G(xi), xi))/G(xi)))^2-a[1]*k^2+(w*a[2]-alpha)*k-w) = 0

(12)

NULL

# rewritting rule

RR := isolate(m+diff(G(xi), xi)/(G(xi))=Phi, diff(G(xi), xi)/G(xi));

(diff(G(xi), xi))/G(xi) = Phi-m

(13)

# Apply RR and collect wrt Phi

subs(RR, L):
normal(%):
PhiN := collect(numer(lhs(%)), phi):
PhiD := denom(lhs(%%));

Phi^3*G(xi)^4

(14)



with(LargeExpressions):

LLE := collect(PhiN, Phi, Veil[phi] ):
LLE / PhiD = 0;

(Phi^6*phi[1]+3*Phi^5*phi[2]-Phi^4*phi[3]-Phi^3*phi[4]-Phi^2*phi[5]+Phi*phi[6]-phi[7])/(Phi^3*G(xi)^4) = 0

(15)

# phi[i] coefficients


phis := [ seq( phi[i] = simplify(Unveil[phi](phi[i]), size), i=1..LastUsed[phi] ) ]:

print~( phis ):

phi[1] = c[1]^3*G(xi)^4*((-gamma+sigma)*k+b)

 

phi[2] = c[0]*G(xi)^4*c[1]^2*((-gamma+sigma)*k+b)

 

phi[3] = -3*G(xi)^4*c[1]*(-(1/3)*a[1]*k^2+(-c[-1]*(gamma-sigma)*c[1]+(-gamma+sigma)*c[0]^2+(1/3)*w*a[2]-(1/3)*alpha)*k+b*c[-1]*c[1]+b*c[0]^2-(1/3)*w)

 

phi[4] = G(xi)*(2*c[1]*(V*a[2]-a[1])*(diff(G(xi), xi))^3+3*c[1]*G(xi)*(2*m*mu+lambda)*(V*a[2]-a[1])*(diff(G(xi), xi))^2+((2*m*mu+lambda)^2*G(xi)+3*mu)*(V*a[2]-a[1])*G(xi)*c[1]*(diff(G(xi), xi))+G(xi)^2*(-c[0]*(6*c[-1]*((-gamma+sigma)*k+b)*c[1]-a[1]*k^2+k*w*a[2]+((-gamma+sigma)*k+b)*c[0]^2-k*alpha-w)*G(xi)+c[1]*mu*(2*m*mu+lambda)*(V*a[2]-a[1])))

 

phi[5] = -3*G(xi)^4*(-(1/3)*a[1]*k^2+(-c[-1]*(gamma-sigma)*c[1]+(-gamma+sigma)*c[0]^2+(1/3)*w*a[2]-(1/3)*alpha)*k+b*c[-1]*c[1]+b*c[0]^2-(1/3)*w)*c[-1]

 

phi[6] = 4*c[-1]*((1/2)*(V*a[2]-a[1])*(diff(G(xi), xi))^3+(3/2)*(m*mu+(1/2)*lambda)*(V*a[2]-a[1])*G(xi)*(diff(G(xi), xi))^2+(V*a[2]-a[1])*((m*mu+(1/2)*lambda)^2*G(xi)+(3/4)*mu)*G(xi)*(diff(G(xi), xi))+(1/2)*G(xi)^2*((3/2)*c[-1]*((-gamma+sigma)*k+b)*c[0]*G(xi)+(m*mu+(1/2)*lambda)*(V*a[2]-a[1])*mu))*G(xi)

 

phi[7] = 8*((1/4)*(V*a[2]-a[1])*(diff(G(xi), xi))^4+(V*a[2]-a[1])*G(xi)*(m*mu+(1/2)*lambda)*(diff(G(xi), xi))^3+(V*a[2]-a[1])*G(xi)*((m*mu+(1/2)*lambda)^2*G(xi)+(1/2)*mu)*(diff(G(xi), xi))^2+(V*a[2]-a[1])*G(xi)^2*(m*mu+(1/2)*lambda)*mu*(diff(G(xi), xi))+(1/4)*G(xi)^2*(-(1/2)*((-gamma+sigma)*k+b)*c[-1]^2*G(xi)^2+mu^2*(V*a[2]-a[1])))*c[-1]

(16)

# WATCHOUT: you have 9 coefficients and so its desirable to have the same number of unknowns

unknowns := indets(rhs~(phis), name);

COEFFS := solve(rhs~(phis), unknowns)

{V, alpha, b, gamma, k, lambda, m, mu, sigma, w, xi, a[1], a[2], c[-1], c[0], c[1]}

 

Error, (in solve) cannot solve expressions with diff(G(xi),xi) for xi

 

NULL

case1 := COEFFS[4]

{alpha = alpha, beta = gamma, delta = delta, gamma = gamma, k = k, lambda = 0, m = 2*n, mu = mu, n = n, sigma = 32*alpha*mu^2*n^4/a[-1]^2, w = -2*alpha*k^2*n-4*alpha*mu^2*n+delta^2, a[-1] = a[-1], a[0] = 0, a[1] = 0}

(17)

NULL

F1 := subs(case1, F)

a[-1]/(2*n+1/(diff(G(xi), xi)))

(18)

F2 := subs(case1, ode)

128*V(xi)^4*n^6*alpha*mu^2/a[-1]^2+(16*alpha*k^2*n^4-8*delta^2*n^3+8*n^3*(-2*alpha*k^2*n-4*alpha*mu^2*n+delta^2))*V(xi)^2-4*V(xi)*(diff(diff(V(xi), xi), xi))*alpha*n^2 = 0

(19)

W := V(xi) = F1

V(xi) = a[-1]/(2*n+1/(diff(G(xi), xi)))

(20)

NULL

E := diff(G(xi), xi) = -(-2*m*mu-lambda)*exp(-(2*m*mu+lambda)*xi)*c__1/(2*m*mu+lambda)-mu/(2*m*mu+lambda)

diff(G(xi), xi) = -(-2*m*mu-lambda)*exp(-(2*m*mu+lambda)*xi)*c__1/(2*m*mu+lambda)-mu/(2*m*mu+lambda)

(21)

W1 := subs(E, W)

V(xi) = a[-1]/(2*n+1/(-(-2*m*mu-lambda)*exp(-(2*m*mu+lambda)*xi)*c__1/(2*m*mu+lambda)-mu/(2*m*mu+lambda)))

(22)

W2 := subs(case1, W1)

V(xi) = a[-1]/(2*n+1/(exp(-4*mu*n*xi)*c__1-(1/4)/n))

(23)

W3 := rhs(V(xi) = a[-1]/(2*n+1/(exp(-4*mu*n*xi)*c__1-(1/4)/n)))

a[-1]/(2*n+1/(exp(-4*mu*n*xi)*c__1-(1/4)/n))

(24)

W4 := convert(W3, trig)

a[-1]/(2*n+1/((cosh(4*mu*n*xi)-sinh(4*mu*n*xi))*c__1-(1/4)/n))

(25)

W5 := W4

a[-1]/(2*n+1/((cosh(4*mu*n*xi)-sinh(4*mu*n*xi))*c__1-(1/4)/n))

(26)

odetest(W2, F2)

0

(27)
 

``

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