Programmer Guide/SPU Reference/DELAY: Difference between revisions

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==<code>[SPU DELAY <var>X</var> OUT <var>Y</var>]</code>==
==<code>[SPU DELAY <var>X</var> OUT <var>Y</var>]</code>==
{|class="einrahmen"
{|class="einrahmen"
!input !!description !!data type !!value type!!default value
!input !!description !!data type !!value type
|-
|-
|<var>X</var>||data to be averaged ||number, vector, matrix ||variable  
|<var>X</var>||input data ||any ||variable  
|-
|-
|<var>TYP</var>||averaging method ||number (int.), string||constant
!output !!description !!data type !!value type
|-
|-
|<var>T</var>||averaging parameter, depends on method ||number or n.c.||<var>TYP</var>=1&rarr;variable<BR><var>TYP</var>&ne;2&rarr;constant
|<var>Y</var>||delayed input data<BR><var>Y</var><sub>t</sub> = <var>X</var><sub>t-1</sub>||same type as <var>X</var>||variable  
|-
|<var>RS</var>||reset flag||number or n.c. ||variable 
|-
!output !!description !!data type !!value type!!comment
|-
|<var>Y</var>||averaged input data ||same type as <var>X</var> ||variable  
|}
|}
;Description:
The averaging algorithm is defined by the inputs <var>TYP</var> and <var>T</var>. The atom averages the elements <var>X</var>[''i'',''j'']<sub>''t''</sub> over evaluation cycles t (''i''=row index, ''j''=column index, ''t''=cycle counter) and stores the averaged value in the element <var>Y</var>[''i'',''j'']<sub>''t''</sub>.
The cycle counter ''t'' is initialized with 0 and incremented by 1 after each evaluation cycle. The cycle counter is reset, if the input <var>RS</var> is set to a value greater than <code>0</code>. The input <var>RS</var> is checked each time the SPU is started.
:;infinite average:
::<var>TYP</var>=<code>0</code> or <code>linear</code>
::<var>T</var>=<code>0</code>
::<math>Y[i,j]_t =
\begin{cases}
X[i,j]_t & \mbox{if }t=0 \\
\frac{1}{t+1}(t.Y[i,j]_{t-1}+X[i,j]_t) & \mbox{if }t>0
\end{cases}
</math>
:;running average:
::<var>TYP</var>=<code>0</code> or <code>linear</code>
::<var>T</var>&gt;<code>0</code>; <var>T</var> is the (integer) number of averaging cycles
::<math>Y[i,j]_t =
\begin{cases}
\frac{1}{t+1}\sum_{z=0}^t X[i,j]_z & \mbox{if }0\leqslant t < T \\
\frac{1}{T}\sum_{z=0}^{T-1}X[i,j]_{t-z} & \mbox{if }t\geqslant T
\end{cases}
</math>
:;exponential average:
::<var>TYP</var>=<code>1</code> or <code>exponential</code>
::<code>0</code>&lt;<var>T</var>&lt;<code>1</code>; <var>T</var> is the averaging factor
::<math>Y[i,j]_t =
\begin{cases}
X[i,j]_t & \mbox{if }t=0\mbox{ (or }T\mbox{ out of range)}\\
\sqrt{T}.Y[i,j]_{t-1}+(1-\sqrt{T}).X[i,j]_t & \mbox{if }t>0
\end{cases}
</math>
:;minimum:
::<var>TYP</var>=<code>2</code> or <code>minimum</code>
::<var>T</var> is not used
::<math>Y[i,j]_t =
\begin{cases}
X[i,j]_t & \mbox{if }t=0 \\
min(Y[i,j]_{t-1},X[i,j]_t) & \mbox{if }t>0
\end{cases}
</math>
:;maximum:
::<var>TYP</var>=<code>3</code> or <code>maximum</code>
::<var>T</var> is not used
::<math>Y[i,j]_t =
\begin{cases}
X[i,j]_t & \mbox{if }t=0 \\
max(Y[i,j]_{t-1},X[i,j]_t) & \mbox{if }t>0
\end{cases}
</math>
;See also:
;See also:
<[[../#Signal Processing Atoms|SP-atoms]]>
<[[../#Signal Processing Atoms|SP-atoms]]>
<!-- AN, 2.5.2011 -->
<!-- AN, 2.5.2011 -->

Latest revision as of 13:38, 6 May 2011

Copies input X to output Y, delaying it by one evaluation step.

[SPU DELAY X OUT Y]

input description data type value type
X input data any variable
output description data type value type
Y delayed input data
Yt = Xt-1
same type as X variable
See also

<SP-atoms>

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