Toni: moved Programmer Guide/SPU Reference/DCTRANS - discrete cosine transform to Programmer Guide/SPU Reference/DCTRANS

2011-04-28T09:57:38Z

moved Programmer Guide/SPU Reference/DCTRANS - discrete cosine transform to Programmer Guide/SPU Reference/DCTRANS

← Older revision	Revision as of 11:57, 28 April 2011
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Admin: 1 revision: Initial import

2010-11-18T16:31:56Z

1 revision: Initial import

← Older revision	Revision as of 18:31, 18 November 2010
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193.171.195.8: initial import

2010-05-17T13:05:27Z

initial import

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{{DISPLAYTITLE:{{SUBPAGENAME}}}}
====DCTRANS - discrete cosine transform====

=====Usage:=====

<code>DCTRANS <var>x</var> <var>dir</var> <var>n</var></code>

=====Inputs:=====

{|
|-
|x
|input vector
|-
|dir
|direction: '<code>Forward</code>' or '<code>Inverse</code>'
|-
|n
|the number of coefficients
|}

=====Outputs:=====

{|
|-
|<var>y</var>
|vector containing result of transformation
|}

=====Function:=====

Discrete Cosine Transform (DCT) <nowiki>-</nowiki> forward and inverse. The DCT is defined as follows:

[[File:3190.png]] for [[File:3191.png]], [[File:3192.png]]for [[File:3193.png]]

The forward DCT is defined by the formula:

[[File:3194.png]]

If <var>dir</var> is <code>Forward</code>:

{|
|-
|if 0 < <var>n</var> < len(<var>x</var>)
|only the first n coefficients are stored in the output
|-
|otherwise
|len(x) coefficients are stored in the output
|}

The definition of the inverse discrete cosine transform is:

[[File:3195.png]]

If <var>dir</var> = <code>Inverse</code>:

{|
|-
|if 0 < n < len(<var>x</var>)
|only the first n coefficients of <var>x</var> are used for the
|-
|
|inverse transformation (the others are set to <code>0</code>);
|-
|
|transformation and output length = len(x)
|-
|if n > len(<var>x</var>)
|vector x is expanded with zeros to length <var>n</var>
|-
|
|transformation and output length = n
|-
|otherwise
|transformation and output length = len(x)
|}

Programmer Guide/SPU Reference/DCTRANS - Revision history

Toni: moved Programmer Guide/SPU Reference/DCTRANS - discrete cosine transform to Programmer Guide/SPU Reference/DCTRANS

Admin: 1 revision: Initial import

193.171.195.8: initial import