dlagf0

Fourier cosine transform by digital filtering

This is a matlab version of dlagf0 originally created by Anderson (1974, 1975, 1983).
A version of matlab can also be found from (Ben Barrowes)
('https://cn.mathworks.com/matlabcentral/fileexchange/11556-dlagf01/content/dlagf01/dlagf0.m')
which is difficult to read for matlab programmers, and also cannot be applied to discrete functions directly.
So I rewrite it by matlab-like expressions, and we can use it for discrete functions directly.
I test three examples provided by Anderson. All Ok, just run test test_dlagf0.m.The main function
is also renamed as dlagf00.m, where 'd' means double-precesion algorithm and the 'f' means Fourier,
'00' means 'Fourier cosine' transform.
Detail is recommend to consult the Readme.md