141 research outputs found
Rational approximations to Tricomi's psi function Interim report, 20 Mar. - 19 Jun. 1968
Closed form rational approximations to Tricomi psi functio
Numerical integration of nonlinear differential equations by use of rational approximation Final report, 15 Jan. 1965 - 14 Jul. 1967
Numerical integration of nonlinear differential equations by use of rational approximatio
Differential-difference properties of generalized Jacobi polynomials Interim report
Differential-difference properties of generalized Jacobi polynomial
Lyapunov exponent and natural invariant density determination of chaotic maps: An iterative maximum entropy ansatz
We apply the maximum entropy principle to construct the natural invariant
density and Lyapunov exponent of one-dimensional chaotic maps. Using a novel
function reconstruction technique that is based on the solution of Hausdorff
moment problem via maximizing Shannon entropy, we estimate the invariant
density and the Lyapunov exponent of nonlinear maps in one-dimension from a
knowledge of finite number of moments. The accuracy and the stability of the
algorithm are illustrated by comparing our results to a number of nonlinear
maps for which the exact analytical results are available. Furthermore, we also
consider a very complex example for which no exact analytical result for
invariant density is available. A comparison of our results to those available
in the literature is also discussed.Comment: 16 pages including 6 figure
Random walk weakly attracted to a wall
We consider a random walk X_n in Z_+, starting at X_0=x>= 0, with transition
probabilities P(X_{n+1}=X_n+1|X_n=y>=1)=1/2-\delta/(4y+2\delta)
P(X_{n+1}=X_n+1|X_n=y>=1)=1/2+\delta/(4y+2\delta) and X_{n+1}=1 whenever X_n=0.
We prove that the expectation value of X_n behaves like n^{1-(\delta/2)} as n
goes to infinity when \delta is in the range (1,2). The proof is based upon the
Karlin-McGregor spectral representation, which is made explicit for this random
walk.Comment: Replacement with minor changes and additions in bibliography. Same
abstract, in plain text rather than Te
Single polymer dynamics in elongational flow and the confluent Heun equation
We investigate the non-equilibrium dynamics of an isolated polymer in a
stationary elongational flow. We compute the relaxation time to the
steady-state configuration as a function of the Weissenberg number. A strong
increase of the relaxation time is found around the coil-stretch transition,
which is attributed to the large number of polymer configurations. The
relaxation dynamics of the polymer is solved analytically in terms of a central
two-point connection problem for the singly confluent Heun equation.Comment: 9 pages, 6 figure
Convergence Acceleration for the Numerical Solution of Second-Order Linear Recurrence Relations
Improved Nearside-Farside Decomposition of Elastic Scattering Amplitudes
A simple technique is described, that provides improved nearside-farside (NF)
decompositions of elastic scattering amplitudes. The technique, involving the
resummation of a Legendre partial wave series, reduces the importance of
unphysical contributions to NF subamplitudes, which can arise in more
conventional NF decompositions. Applications are made to a strong absorption
model and to a O + C optical potential at
MeV.Comment: 5 pages, 2 figure
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