diff --git a/doc/sf_and_dist/equations/laplace_pdf.mml b/doc/sf_and_dist/equations/laplace_pdf.mml
new file mode 100644
index 000000000..6ba8cc8d2
--- /dev/null
+++ b/doc/sf_and_dist/equations/laplace_pdf.mml
@@ -0,0 +1,52 @@
+<?xml version='1.0'?>
+<!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN'
+  'http://www.w3.org/TR/MathML2/dtd/xhtml-math11-f.dtd'
+  [<!ENTITY mathml 'http://www.w3.org/1998/Math/MathML'>]>
+<html xmlns='http://www.w3.org/1999/xhtml'>
+<head><title>laplace_pdf</title>
+</head>
+<body>
+<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
+  <mrow>
+    <mtext>f</mtext>
+    <mfenced>
+      <mrow>
+        <mi>x</mi>
+        <mo>;</mo>
+        <mi>&#x03BC;</mi>
+        <mo>,</mo>
+        <mi>&#x03C3;</mi>
+      </mrow>
+    </mfenced>
+    <mspace width="1em"/>
+    <mo>=</mo>
+    <mspace width="1em"/>
+    <mfrac>
+      <mn>1</mn>
+      <mrow>
+        <mn>2</mn>
+        <mi>&#x03C3;</mi>
+      </mrow>
+    </mfrac>
+    <msup>
+      <mi>e</mi>
+      <mrow>
+        <mo>&#x2212;</mo>
+        <mfrac>
+          <mrow>
+            <mo>|</mo>
+            <mi>x</mi>
+            <mo>&#x2212;</mo>
+            <mi>&#x03BC;</mi>
+            <mo>|</mo>
+          </mrow>
+          <mrow>
+            <mi>&#x03C3;</mi>
+          </mrow>
+        </mfrac>
+      </mrow>
+    </msup>
+  </mrow>
+</math>
+</body>
+</html>
\ No newline at end of file
