# NAME

Math::Wavelet::Haar - Perl extension for transforming data with the Haar Wavelet

# SYNOPSIS

``````  use Math::Wavelet::Haar qw(:all);

my @test = qw(1 2 3 4 5 6 7 8);
my @result = transform1D(@test);

my @test = ([0,1,2,3],[1,2,3,4],[2,3,4,5],[3,4,5,6]);
my @result = transform2D(@test);

my @test = qw(36 -16 -4 -4 -1 -1 -1 -1);
my @result = detransform1D(@test);

my @test = ([48,-16,-4,-4],[-16,0,0,0],[-4,0,0,0],[-4,0,0,0]);
my @result = detransform2D(@test);

my @test = ([48,-16,-4,-4],[-16,0,0,0],[-4,0,0,0],[-4,0,0,0]);
@result = detransform2D(transform2D(@test));

@result == @test;``````

# DESCRIPTION

Math::Wavelet::Haar is a module for performing a discrete wavelet transform using the Haar wavelet.

## EXPORT

transform1D @result = transform1D(@input); takes a single array as input, and returns the transformed result, @input MUST be a power of two in length, if it is not, then it will return undef
transform2D @result = transform2D(@input); takes a single two dimensional array as input, and returns the transformed result, @input MUST be a power of two in length and width, if it is not, then it will return undef
detransform1D @result = detransform1D(@input); takes a single array as input, and returns the inverse transform as the result, @input MUST be a power of two in length, if it is not, then it will return undef
detransform2D @result = detransform2D(@input); takes a single two dimensional array as input, and returns the inverse transform as the result, @input MUST be a power of two in length and width, if it is not, then it will return undef

Wikipedia articles on the Haar Wavlet, Discrete Wavelet Transforms, and lots and lots of math

# CHANGES

v0.01 First release, supports only transforming
v0.02 Second release, supports transforming and its inverse Changed API significatly
v0.05 Third public release, fixes catastrophic bug that causes the input to the 2d transforms to be mangled
v0.06 Added some corrected dependencies and marked the module as usable by earlier perl versions Also removed an incorrect print statement, that outputted debugging information that shouldn't have been outputted

# AUTHOR

Ryan Voots <lt>simcop2387@yahoo.com<gt>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.

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