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lua/WalshTransform.lua  view on Meta::CPAN

--                        www.pjb.com.au                             --
--                                                                   --
--   This module is free software; you can redistribute it and/or    --
--          modify it under the same terms as Lua5 itself.           --
-- ----------------------------------------------------------------- --
local M = {} -- public interface
M.Version = '1.17'
M.VersionDate = '12aug2010'

-- Example usage:
-- local WT = require 'WalshTransform'
-- H = WT.fht(a)

--------------------- infrastructure ----------------------
local function warn(str)
    io.stderr:write(str,'\n')
end
local function die(str)
    io.stderr:write(str,'\n')
    os.exit(1)
end

lua/WalshTransform.lua  view on Meta::CPAN

--[[

=pod

=head1 NAME

WalshTransform.lua - Fast Hadamard and Walsh Transforms

=head1 SYNOPSIS

 local WT = require 'WalshTransform' -- name doesn't matter of course
 local f = {1.618, 2.718, 3.142, 4.669}  -- must be power-of-two long
 local FH1 = WT.fht(f)   -- Hadamard transform
 local fh1 = WT.fhtinv(FH1)
 -- or
 local FW2 = WT.fwt(f)   -- Walsh transform
 local fw2 = WT.fwtinv(FW2)
 local FH2 = WT.walsh2hadamard(FW2)

 local PS  = WT.power_spectrum(f)

lua/test.lua  view on Meta::CPAN

function ok(b,s)
	i_test = i_test + 1
	if b then
		io.write('ok '..i_test..' - '..s.."\n")
	else
		io.write('not ok '..i_test..' - '..s.."\n")
		Failed = Failed + 1
	end
end
--------------------------- infrastructure ----------------
local M = require 'WalshTransform'

local x = {0,2,2,0};
local X = M.fht(x);
ok (equal(X, {1,0,0,-1}), "Hadamard transform");
X = M.fwt(x);
--io.write('X = '..table.concat(X,', ').."\n")
ok (equal(X, {1,0,-1,0}), "Walsh transform");

ok (equal(M.fhtinv{1,0,0,-1}, {0,2,2,0}), "Inverse Hadamard transform");
local IWT = M.fwtinv{1,0,-1,0}