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Manuscript Title: Solution of Raman-Nath equations.
Authors: R. Coisson, D. Zavattaro
Program title: RANA
Catalogue identifier: ACNM_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 76(1993)231
Programming language: Matlab.
Computer: PC or VAX.
Operating system: MS-DOS or Unix or VMS.
RAM: 512K words
Keywords: Raman-nath equations, Parametric equations, Diffraction theory, Electromagnetic.
Classification: 10.

Nature of problem:
Evolution of a wave in a sinusoidal potential. In particular, diffraction of a wave from a thick sinusoidal grating or acoustic wave. Also used in the theory of the free electron laser and in interaction of radiation with multilevel material system.

Solution method:
Eigenvectors of the matrix representing interaction between different component waves are found and propagated from initial conditions.

Restrictions:
The matrix order is chosen in order to get an accuracy of the order of 0.1 per cent for values of the third variable not exceeding 5. For other cases of higher precision, the user can change the variable "nO" in the program.

Unusual features:
(Possible adaptations) Input wave not in a single mode (as in linearised self-diffraction), refractive index modulation wavevector not perpendicular to plane where initial conditions are defined, nonsinusoidal index variation (for example dynamical X-ray or electron diffraction in crystals), calculation of Mathieu functions.

Running time:
From a few seconds to tens of seconds for a matrix (for example 7x100) of results.

References:
[1] Produced by The MathWorks, Inc., 21, Eliot St., South Natick, Maryland 01760, U.S.A. (fax (1)508-6532997).