chebyshev_polynomial, a FORTRAN77 code which considers the Chebyshev polynomials T(i,x), U(i,x), V(i,x) and W(i,x). Functions are provided to evaluate the polynomials, determine their zeros, produce their polynomial coefficients, produce related quadrature rules, project other functions onto these polynomial bases, and integrate double and triple products of the polynomials.
The Chebyshev polynomial T(n,x), or Chebyshev polynomial of the first kind, may be defined, for 0 <= n, and -1 <= x <= +1 by:
cos ( t ) = x T(n,x) = cos ( n * t )For any value of x, T(n,x) may be evaluated by a three term recurrence:
T(0,x) = 1 T(1,x) = x T(n+1,x) = 2x T(n,x) - T(n-1,x)
The Chebyshev polynomial U(n,x), or Chebyshev polynomial of the second kind, may be defined, for 0 <= n, and -1 <= x <= +1 by:
cos ( t ) = x U(n,x) = sin ( ( n + 1 ) t ) / sin ( t )For any value of x, U(n,x) may be evaluated by a three term recurrence:
U(0,x) = 1 U(1,x) = 2x U(n+1,x) = 2x U(n,x) - U(n-1,x)
The Chebyshev polynomial V(n,x), or Chebyshev polynomial of the third kind, may be defined, for 0 <= n, and -1 <= x <= +1 by:
cos ( t ) = x V(n,x) = cos ( (2n+1)*t/2) / cos ( t/2)For any value of x, V(n,x) may be evaluated by a three term recurrence:
V(0,x) = 1 V(1,x) = 2x-1 V(n+1,x) = 2x V(n,x) - V(n-1,x)
The Chebyshev polynomial W(n,x), or Chebyshev polynomial of the fourth kind, may be defined, for 0 <= n, and -1 <= x <= +1 by:
cos ( t ) = x W(n,x) = sin((2*n+1)*t/2)/sin(t/2)For any value of x, W(n,x) may be evaluated by a three term recurrence:
W(0,x) = 1 W(1,x) = 2x+1 W(n+1,x) = 2x W(n,x) - W(n-1,x)
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
chebyshev_polynomial is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version and a Python version.
bernstein_polynomial, a FORTRAN77 library which evaluates the Bernstein polynomials, useful for uniform approximation of functions;
CHEBYSHEV, a FORTRAN90 library which computes the Chebyshev interpolant/approximant to a given function over an interval.
CHEBYSHEV_SERIES, a FORTRAN77 library which can evaluate a Chebyshev series approximating a function f(x), while efficiently computing one, two or three derivatives of the series, which approximate f'(x), f''(x), and f'''(x), by Manfred Zimmer.
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CHEBYSHEV2_RULE, a FORTRAN90 program which compute and print a Gauss-Chebyshev type 2 quadrature rule.
HERMITE_POLYNOMIAL, a FORTRAN77 library which evaluates the physicist's Hermite polynomial, the probabilist's Hermite polynomial, the Hermite function, and related functions.
INT_EXACTNESS_CHEBYSHEV1, a FORTRAN90 program which tests the polynomial exactness of Gauss-Chebyshev type 1 quadrature rules.
INT_EXACTNESS_CHEBYSHEV2, a FORTRAN90 program which tests the polynomial exactness of Gauss-Chebyshev type 2 quadrature rules.
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LEGENDRE_POLYNOMIAL, a FORTRAN77 library which evaluates the Legendre polynomial and associated functions.
POLPAK, a FORTRAN77 library which evaluates a variety of mathematical functions.
TEST_VALUES, a FORTRAN77 library which supplies test values of various mathematical functions.