1 files changed, 43 insertions, 1 deletions
diff --git a/help/en_US/ifwht.xml b/help/en_US/ifwht.xml
index 37903a0..c746dcd 100644
--- a/help/en_US/ifwht.xml
+++ b/help/en_US/ifwht.xml
@@ -17,7 +17,49 @@
 
   <refnamediv>
     <refname>ifwht</refname>
-    <refpurpose></refpurpose>
+    <refpurpose>Compute the inverse Walsh-Hadamard transform of x using the Fast Walsh-Hadamard Transform (FWHT) algorithm</refpurpose>
   </refnamediv>
 
+
+<refsynopsisdiv>
+   <title>Calling Sequence</title>
+   <synopsis>
+   ifwht (x)
+   ifwht (x, n)
+   ifwht (x, n, order)
+   </synopsis>
+</refsynopsisdiv>
+
+<refsection>
+   <title>Parameters</title>
+   <variablelist>
+   <varlistentry><term>x:</term>
+      <listitem><para> real or complex valued scalar or vector</para></listitem></varlistentry>
+   <varlistentry><term>n:</term>
+      <listitem><para> Input is truncated or extended to have a length of n</para></listitem></varlistentry>
+   <varlistentry><term>order:</term>
+      <listitem><para> Specifies the order in which the returned inverse Walsh-Hadamard transform</para></listitem></varlistentry>
+   </variablelist>
+</refsection>
+
+<refsection>
+   <title>Description</title>
+   <para>
+Compute the inverse Walsh-Hadamard transform of x using the Fast Walsh-Hadamard Transform (FWHT) algorithm. If the input is a matrix, the inverse FWHT is calculated along the columns of x.
+The number of elements of x must be a power of 2; if not, the input will be extended and filled with zeros. If a second argument is given, the input is truncated or extended to have length n.
+The third argument specifies the order in which the returned inverse Walsh-Hadamard transform coefficients should be arranged. The order may be any of the following strings:
+   </para>
+   <para>
+"sequency"
+The coefficients are returned in sequency order. This is the default if order is not given.
+   </para>
+   <para>
+"hadamard"
+The coefficients are returned in Hadamard order.
+   </para>
+   <para>
+"dyadic"
+The coefficients are returned in Gray code order.
+</para>
+</refsection>
 </refentry>