final commit

1 files changed, 41 insertions, 1 deletions

diff --git a/help/en_US/periodogram.xml b/help/en_US/periodogram.xml
index 8b5b2ed..5ad8738 100644
--- a/help/en_US/periodogram.xml
+++ b/help/en_US/periodogram.xml
@@ -17,7 +17,47 @@
 
   <refnamediv>
     <refname>periodogram</refname>
-    <refpurpose>funcprot(0);</refpurpose>
+    <refpurpose>Return the periodogram (Power Spectral Density) of X</refpurpose>
   </refnamediv>
 
+
+<refsynopsisdiv>
+   <title>Calling Sequence</title>
+   <synopsis>
+   [PXX, W] = periodogram (X)
+   [PXX, W] = periodogram (X, WIN)
+   [PXX, W] = periodogram (X, WIN, NFFT)
+   [PXX, W] = periodogram (X, WIN, NFFT, FS)
+   [PXX, W] = periodogram (..., "RANGE")
+   </synopsis>
+</refsynopsisdiv>
+
+<refsection>
+   <title>Parameters</title>
+   <variablelist>
+   <varlistentry><term>X:</term>
+      <listitem><para>data vector.  If X is real-valued a one-sided spectrum is estimated. If X is complex-valued, or "RANGE" specifies "twosided", the full spectrum is estimated.</para></listitem></varlistentry>
+   <varlistentry><term>WIN:</term>
+      <listitem><para> window weight data.  If window is empty or unspecified a default rectangular window is used.  Otherwise, the window is applied to the signal ('X .* WIN') before computing th periodogram.  The window data must be a vector of the same length as X.</para></listitem></varlistentry>
+   <varlistentry><term>NFFT:</term>
+      <listitem><para>number of frequency bins.  The default is 256 or the next higher power of 2 greater than the length of X ('max (256,2.^nextpow2 (length (x)))').  If NFFT is greater than the length of the input then X will be zero-padded to the length of NFFT.</para></listitem></varlistentry>
+   <varlistentry><term>FS:</term>
+      <listitem><para>sampling rate.  The default is 1.</para></listitem></varlistentry>
+   <varlistentry><term>RANGE:</term>
+      <listitem><para>range of spectrum.  "onesided" computes spectrum from [0..nfft/2+1]."twosided" computes spectrum from [0..nfft-1].</para></listitem></varlistentry>
+   </variablelist>
+</refsection>
+
+<refsection>
+   <title>Description</title>
+   <para>
+The optional second output W are the normalized angular frequencies.  For a one-sided calculation W is in the range [0, pi]. If NFFT is even and [0, pi) if NFFT is odd.  Similarly, for a two-sided calculation W is in the range [0, 2*pi] or [0, 2*pi)depending on NFFT.
+   </para>
+   <para>
+If a sampling frequency is specified, FS, then the output frequencies F will be in the range [0, FS/2] or [0, FS/2) for one-sided calculations. For two-sided calculations the range will be [0, FS).
+   </para>
+   <para>
+When called with no outputs the periodogram is immediately plotted in the current figure window.
+</para>
+</refsection>
 </refentry>