Titchmarsh ODEs
Description
Examples
The general form of the Titchmarsh ODE is given by:
Titchmarsh_ode := diff(y(x),x,x)+(lambda-x^(2*n))*y(x)=0;
Titchmarsh_ode≔ⅆ2ⅆx2y⁡x+λ−x2⁢n⁢y⁡x=0
where n is an integer. See Hille, "Lectures on Ordinary Differential Equations", p. 617.
All linear second order homogeneous ODEs can be transformed into first order ODEs of Riccati type by giving the symmetry [0,y] to dsolve (all linear homogeneous ODEs have this symmetry) or by calling convert (see convert,ODEs).
with⁡DEtools,odeadvisor:
odeadvisor⁡Titchmarsh_ode
_Titchmarsh
Reduction to Riccati by giving the symmetry to dsolve
ans≔dsolve⁡Titchmarsh_ode,HINT=0,y
ans≔y⁡x=ⅇ∫_b⁡_aⅆ_a+c__1whereⅆⅆ_a_b⁡_a=−_b⁡_a2+_a2⁢n−λ,_a=x,_b⁡_a=ⅆⅆxy⁡xy⁡x,x=_a,y⁡x=ⅇ∫_b⁡_aⅆ_a+c__1
The reduced ODE above is of Riccati type:
reduced_ode≔op⁡2,2,1,1,ans
reduced_ode≔ⅆⅆ_a_b⁡_a=−_b⁡_a2+_a2⁢n−λ
odeadvisor⁡reduced_ode
_Riccati
Converting this ODE into a first order ODE of Riccati type
Riccati_ode_TR≔convert⁡Titchmarsh_ode,Riccati
Riccati_ode_TR≔ⅆⅆx_a⁡x=_F1⁡x⁢_a⁡x2−ⅆⅆx_F1⁡x⁢_a⁡x_F1⁡x+λ−x2⁢n_F1⁡x,y⁡x=ⅇ−∫_a⁡x⁢_F1⁡xⅆx⁢c__1
In the answer returned by convert, there are the Riccati ODE and the transformation of variables used. Changes of variables in ODEs can be performed using ?PDEtools[dchange]. For example, using the transformation of variables above, we can recover the result returned by convert.
See Also
DEtools
odeadvisor
dsolve
quadrature
missing
reducible
linear_ODEs
exact_linear
exact_nonlinear
sym_Fx
linear_sym
Bessel
Painleve
Halm
Gegenbauer
Duffing
ellipsoidal
elliptic
erf
Emden
Jacobi
Hermite
Lagerstrom
Laguerre
Liouville
Lienard
Van_der_Pol
Titchmarsh
odeadvisor,types
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