lanczos.m

% FILE: lanczos.m
% 
% FUNCTION: lanczos
% 
% CALL: h = lanczos(M, L)
% 
% Returns the values of a lanczos window of length M using the extra
% parameter L 
% 
% INPUTS:
%         M - length of the returned window
%         L - gives the oppening of the window, recomanded values 
%             L in [1, 3]
% OUTPUTS:
%           h - the values of a lanczos window of length M and parameter L
% 
% Author:  Leonard-Gabriel Necula
% Created: December 24 2020
% Updated: January  18 2021
function h = lanczos(M, L)

    if nargin < 1

        display('No input parameters detected.');
        display('Setting M = 128 and L = 1.5');
        L = 1.5;
        M = 128;
    end
    if isempty(M)

        display('Detected empty M.');
        display('Setting M = 128');
        M = 128;
    end
    if nargin < 2
        display('L missing.');
        display('Setting L = 1.5');
        L = 1.5;
    end
    if isempty(L)

        display('Detected empty L.');
        display('Setting L = 1.5');
        L = 1.5;

    end
% ---------------------------------------------------------------------- %

    N = 0: M - 1;
    arg = (2*pi * (2*N - M + 1))./(2*(M-1));

    h = sin(arg)./arg;
    if mod(M, 2)
        h((M-1)/2 + 1) = 1;
    end
    h = h.^L;
    

end