From 1572284ed3ed5abe25d71ae520b3e9e758f7c3ce Mon Sep 17 00:00:00 2001
From: Yuji Uchiyama <uchiyama@php.net>
Date: Tue, 1 Aug 2017 21:15:55 +0000
Subject: [PATCH] Add documents for stats functions

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@342758 c90b9560-bf6c-de11-be94-00142212c4b1
---
 reference/stats/functions/stats-den-uniform.xml  | 14 ++++++++++----
 reference/stats/functions/stats-dens-beta.xml    | 14 ++++++++++----
 reference/stats/functions/stats-dens-cauchy.xml  | 14 ++++++++++----
 .../stats/functions/stats-dens-chisquare.xml     | 13 +++++++++----
 .../stats/functions/stats-dens-exponential.xml   | 13 +++++++++----
 reference/stats/functions/stats-dens-f.xml       | 14 ++++++++++----
 reference/stats/functions/stats-dens-gamma.xml   | 14 ++++++++++----
 reference/stats/functions/stats-dens-laplace.xml | 14 ++++++++++----
 .../stats/functions/stats-dens-logistic.xml      | 14 ++++++++++----
 .../functions/stats-dens-negative-binomial.xml   | 14 ++++++++++----
 .../stats/functions/stats-dens-pmf-binomial.xml  | 14 ++++++++++----
 .../functions/stats-dens-pmf-hypergeometric.xml  | 16 ++++++++++++----
 .../stats/functions/stats-dens-pmf-poisson.xml   | 12 ++++++++----
 reference/stats/functions/stats-dens-t.xml       | 13 +++++++++----
 reference/stats/functions/stats-dens-weibull.xml | 14 ++++++++++----
 15 files changed, 147 insertions(+), 60 deletions(-)

diff --git a/reference/stats/functions/stats-den-uniform.xml b/reference/stats/functions/stats-den-uniform.xml
index bd571f4d7e..6a446335ad 100644
--- a/reference/stats/functions/stats-den-uniform.xml
+++ b/reference/stats/functions/stats-den-uniform.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-den-uniform" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_den_uniform</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the uniform distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>a</parameter></methodparam>
    <methodparam><type>float</type><parameter>b</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the uniform distribution of which the lower bound is
+   <parameter>a</parameter> and the upper bound is <parameter>b</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>a</parameter></term>
      <listitem>
       <para>
+       The lower bound of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>b</parameter></term>
      <listitem>
       <para>
+       The upper bound of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-beta.xml b/reference/stats/functions/stats-dens-beta.xml
index c8c96d99b9..1e9c3aa741 100644
--- a/reference/stats/functions/stats-dens-beta.xml
+++ b/reference/stats/functions/stats-dens-beta.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-beta" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_beta</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the beta distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>a</parameter></methodparam>
    <methodparam><type>float</type><parameter>b</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the beta distribution of which the shape parameters
+   are <parameter>a</parameter> and <parameter>b</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,12 +27,14 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
     <varlistentry>
      <term><parameter>a</parameter></term>
      <listitem>
+       The shape parameter of the distribution
       <para>
       </para>
      </listitem>
@@ -39,6 +43,7 @@
      <term><parameter>b</parameter></term>
      <listitem>
       <para>
+       The shape parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-cauchy.xml b/reference/stats/functions/stats-dens-cauchy.xml
index 9c5f494ab6..3048d0833c 100644
--- a/reference/stats/functions/stats-dens-cauchy.xml
+++ b/reference/stats/functions/stats-dens-cauchy.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-cauchy" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_cauchy</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the Cauchy distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>ave</parameter></methodparam>
    <methodparam><type>float</type><parameter>stdev</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the Cauchy distribution whose location and scale are
+   <parameter>ave</parameter> and <parameter>stdev</parameter>, respectively.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>ave</parameter></term>
      <listitem>
       <para>
+       The location parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>stdev</parameter></term>
      <listitem>
       <para>
+       The scale parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-chisquare.xml b/reference/stats/functions/stats-dens-chisquare.xml
index 211821b0b0..812fb4ad30 100644
--- a/reference/stats/functions/stats-dens-chisquare.xml
+++ b/reference/stats/functions/stats-dens-chisquare.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-chisquare" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_chisquare</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the chi-square distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -12,9 +12,11 @@
    <methodparam><type>float</type><parameter>x</parameter></methodparam>
    <methodparam><type>float</type><parameter>dfr</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the chi-square distribution of which the degree of
+   freedom is <parameter>dfr</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -24,6 +26,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -31,6 +34,7 @@
      <term><parameter>dfr</parameter></term>
      <listitem>
       <para>
+       The degree of freedom of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -41,6 +45,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-exponential.xml b/reference/stats/functions/stats-dens-exponential.xml
index 6c1baab6f5..dffa0e5e15 100644
--- a/reference/stats/functions/stats-dens-exponential.xml
+++ b/reference/stats/functions/stats-dens-exponential.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-exponential" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_exponential</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the exponential distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -12,9 +12,11 @@
    <methodparam><type>float</type><parameter>x</parameter></methodparam>
    <methodparam><type>float</type><parameter>scale</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the exponential distribution of which the scale is
+   <parameter>scale</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -24,6 +26,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -31,6 +34,7 @@
      <term><parameter>scale</parameter></term>
      <listitem>
       <para>
+       The scale of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -41,6 +45,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-f.xml b/reference/stats/functions/stats-dens-f.xml
index 7a9450849a..b1eb378007 100644
--- a/reference/stats/functions/stats-dens-f.xml
+++ b/reference/stats/functions/stats-dens-f.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-f" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_f</refname>
-  <refpurpose></refpurpose>
+  <refpurpose>Probability density function of the F distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>dfr1</parameter></methodparam>
    <methodparam><type>float</type><parameter>dfr2</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the F distribution of which the degree of freedoms
+   are <parameter>dfr1</parameter> and <parameter>dfr2</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>dfr1</parameter></term>
      <listitem>
       <para>
+       The degree of freedom of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>dfr2</parameter></term>
      <listitem>
       <para>
+       The degree of freedom of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-gamma.xml b/reference/stats/functions/stats-dens-gamma.xml
index 01b01df5b6..7493ecf771 100644
--- a/reference/stats/functions/stats-dens-gamma.xml
+++ b/reference/stats/functions/stats-dens-gamma.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-gamma" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_gamma</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the gamma distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>shape</parameter></methodparam>
    <methodparam><type>float</type><parameter>scale</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the gamma distribution of which the shape parameter
+   is <parameter>shape</parameter> and the scale parameter is <parameter>scale</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>shape</parameter></term>
      <listitem>
       <para>
+       The shape parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>scale</parameter></term>
      <listitem>
       <para>
+       The scale parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-laplace.xml b/reference/stats/functions/stats-dens-laplace.xml
index 0ccd17a43e..e2443edb84 100644
--- a/reference/stats/functions/stats-dens-laplace.xml
+++ b/reference/stats/functions/stats-dens-laplace.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-laplace" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_laplace</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the Laplace distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>ave</parameter></methodparam>
    <methodparam><type>float</type><parameter>stdev</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the Laplace distribution of which the location parameter
+   is <parameter>ave</parameter> and the scale parameter is <parameter>stdev</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>ave</parameter></term>
      <listitem>
       <para>
+       The location parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>stdev</parameter></term>
      <listitem>
       <para>
+       The shape parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-logistic.xml b/reference/stats/functions/stats-dens-logistic.xml
index c8bef5e4d0..189a4c5326 100644
--- a/reference/stats/functions/stats-dens-logistic.xml
+++ b/reference/stats/functions/stats-dens-logistic.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-logistic" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_logistic</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the logistic distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>ave</parameter></methodparam>
    <methodparam><type>float</type><parameter>stdev</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the gamma distribution of which the location parameter
+   is <parameter>ave</parameter> and the scale parameter is <parameter>stdev</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>ave</parameter></term>
      <listitem>
       <para>
+       The location parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>stdev</parameter></term>
      <listitem>
       <para>
+       The shape parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-negative-binomial.xml b/reference/stats/functions/stats-dens-negative-binomial.xml
index 0739425b7c..7c515623b9 100644
--- a/reference/stats/functions/stats-dens-negative-binomial.xml
+++ b/reference/stats/functions/stats-dens-negative-binomial.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-negative-binomial" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_negative_binomial</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the negative binomial distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>n</parameter></methodparam>
    <methodparam><type>float</type><parameter>pi</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the negative binomial distribution of which the number of the success
+   is <parameter>n</parameter> and the success rate is <parameter>pi</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>n</parameter></term>
      <listitem>
       <para>
+       The number of the success of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>pi</parameter></term>
      <listitem>
       <para>
+       The success rate of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-pmf-binomial.xml b/reference/stats/functions/stats-dens-pmf-binomial.xml
index b318acffc0..3f6422c6da 100644
--- a/reference/stats/functions/stats-dens-pmf-binomial.xml
+++ b/reference/stats/functions/stats-dens-pmf-binomial.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-pmf-binomial" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_pmf_binomial</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability mass function of the binomial distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>n</parameter></methodparam>
    <methodparam><type>float</type><parameter>pi</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability mass at <parameter>x</parameter>, where the random variable
+   follows the binomial distribution of which the number of trials is <parameter>n</parameter>
+   and the success rate is <parameter>pi</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability mass is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>n</parameter></term>
      <listitem>
       <para>
+       The number of trials of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>pi</parameter></term>
      <listitem>
       <para>
+       The success rate of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability mass at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-pmf-hypergeometric.xml b/reference/stats/functions/stats-dens-pmf-hypergeometric.xml
index b93b4507a8..26867dbac0 100644
--- a/reference/stats/functions/stats-dens-pmf-hypergeometric.xml
+++ b/reference/stats/functions/stats-dens-pmf-hypergeometric.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-pmf-hypergeometric" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_pmf_hypergeometric</refname>
-  <refpurpose></refpurpose>
+  <refpurpose>Probability mass function of the hypergeometric distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -14,9 +14,12 @@
    <methodparam><type>float</type><parameter>N1</parameter></methodparam>
    <methodparam><type>float</type><parameter>N2</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability mass at <parameter>n1</parameter>, where the random variable
+   follows the hypergeometric distribution of which the number of failure is
+   <parameter>n2</parameter>, the number of success samples is <parameter>N1</parameter>,
+   and the number of failure samples is <parameter>N2</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -26,6 +29,7 @@
      <term><parameter>n1</parameter></term>
      <listitem>
       <para>
+       The number of success, at which the probability mass is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -33,6 +37,7 @@
      <term><parameter>n2</parameter></term>
      <listitem>
       <para>
+       The number of failure of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -40,6 +45,7 @@
      <term><parameter>N1</parameter></term>
      <listitem>
       <para>
+       The number of success samples of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -47,6 +53,7 @@
      <term><parameter>N2</parameter></term>
      <listitem>
       <para>
+       The number of failure samples of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -57,6 +64,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability mass at <parameter>n1</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-pmf-poisson.xml b/reference/stats/functions/stats-dens-pmf-poisson.xml
index ba130c820a..633aee3c8f 100644
--- a/reference/stats/functions/stats-dens-pmf-poisson.xml
+++ b/reference/stats/functions/stats-dens-pmf-poisson.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-pmf-poisson" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_pmf_poisson</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability mass function of the Poisson distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -12,9 +12,10 @@
    <methodparam><type>float</type><parameter>x</parameter></methodparam>
    <methodparam><type>float</type><parameter>lb</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability mass at <parameter>x</parameter>, where the random variable
+   follows the Poisson distribution whose parameter is <parameter>lb</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -24,6 +25,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability mass is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -31,6 +33,7 @@
      <term><parameter>lb</parameter></term>
      <listitem>
       <para>
+       The parameter of the Poisson distribution
       </para>
      </listitem>
     </varlistentry>
@@ -41,6 +44,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability mass at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-t.xml b/reference/stats/functions/stats-dens-t.xml
index 5fdb71abfa..1f5415b7e6 100644
--- a/reference/stats/functions/stats-dens-t.xml
+++ b/reference/stats/functions/stats-dens-t.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-t" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_t</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the t-distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -12,9 +12,11 @@
    <methodparam><type>float</type><parameter>x</parameter></methodparam>
    <methodparam><type>float</type><parameter>dfr</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the t-distribution of which the degree of
+   freedom is <parameter>dfr</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -24,6 +26,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -31,6 +34,7 @@
      <term><parameter>dfr</parameter></term>
      <listitem>
       <para>
+       The degree of freedom of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -41,6 +45,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>
 
diff --git a/reference/stats/functions/stats-dens-weibull.xml b/reference/stats/functions/stats-dens-weibull.xml
index 7757579c18..8db137ad5f 100644
--- a/reference/stats/functions/stats-dens-weibull.xml
+++ b/reference/stats/functions/stats-dens-weibull.xml
@@ -3,7 +3,7 @@
 <refentry xml:id="function.stats-dens-weibull" xmlns="http://docbook.org/ns/docbook">
  <refnamediv>
   <refname>stats_dens_weibull</refname>
-  <refpurpose>Not documented</refpurpose>
+  <refpurpose>Probability density function of the Weibull distribution</refpurpose>
  </refnamediv>
  <refsect1 role="description">
   &reftitle.description;
@@ -13,9 +13,11 @@
    <methodparam><type>float</type><parameter>a</parameter></methodparam>
    <methodparam><type>float</type><parameter>b</parameter></methodparam>
   </methodsynopsis>
-
-  &warn.undocumented.func;
-
+  <para>
+   Returns the probability density at <parameter>x</parameter>, where the
+   random variable follows the gamma distribution of which the shape parameter
+   is <parameter>a</parameter> and the scale parameter is <parameter>b</parameter>.
+  </para>
  </refsect1>
  <refsect1 role="parameters">
   &reftitle.parameters;
@@ -25,6 +27,7 @@
      <term><parameter>x</parameter></term>
      <listitem>
       <para>
+       The value at which the probability density is calculated
       </para>
      </listitem>
     </varlistentry>
@@ -32,6 +35,7 @@
      <term><parameter>a</parameter></term>
      <listitem>
       <para>
+       The shape parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -39,6 +43,7 @@
      <term><parameter>b</parameter></term>
      <listitem>
       <para>
+       The scale parameter of the distribution
       </para>
      </listitem>
     </varlistentry>
@@ -49,6 +54,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
+   The probability density at <parameter>x</parameter> or &false; for failure.
   </para>
  </refsect1>