POLYNOMIAL APPROXIMATION

This directory contains simple C++ classes, which are not part of the main LORENE library.

These classes are intended to illustrate polynomial approximation to functions (mainly interpolation on various grids). There are two families of classes:

• Grid : grids as sampling of [-1,1], declared in the file grid.h
• Ortho_poly : orthogonal polynomials, declared in the file ortho_poly.h

There are also some simple graphical routines (declared in the file plot.h), which provides provides an interface to PGPLOT, in order to perform easily some drawings (X11, EPS or PNG). See Modules -> Basic graphical routines

The main codes are

• es.C : test code for class Grid
• runge.C : exhibition of Runge's phenomenon
• cheby.C : Chebyshev expansions
• legendre.C : Legendre expansions
• interpole.C : comparison of various interpolations of a function
• approx_ortho.C : approximation of a function by orthogonal polynomials

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