From a0579526c0c770c9b126e517c171e8505cc9695a Mon Sep 17 00:00:00 2001
From: scemama <scemama@users.noreply.github.com>
Date: Wed, 4 Nov 2020 23:47:05 +0000
Subject: [PATCH] deploy: 2467214b3a0741bd65f7304ac054adabbb3449e0

---
 README.html         |  13 +-
 qmckl.html          |   4 +-
 qmckl_ao.html       | 260 ++++++++++++++++++++++++++++++----
 qmckl_context.html  | 336 ++++++++++++++++++++++++++++++++++++++------
 qmckl_distance.html |   4 +-
 qmckl_memory.html   |   4 +-
 test_qmckl.html     |   4 +-
 7 files changed, 547 insertions(+), 78 deletions(-)
diff --git a/README.html b/README.html
index 181fde4..f1283c5 100644
--- a/README.html
+++ b/README.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>QMCkl source code documentation</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -308,6 +308,11 @@ those exposed in the API suffixed by <code>_f</code>.
 Fortran interface files should also be written in a file with a
 <code>.fh</code> extension.
 </p>
+
+<p>
+For more guidelines on using Fortran to generate a C interface, see
+<a href="http://fortranwiki.org/fortran/show/Generating+C+Interfaces">this link</a>
+</p>
 </div>
 </div>
 
@@ -395,6 +400,10 @@ and terminated by a zero character (C convention).
 </li>
 </ul>
 
+<p>
+Complex numbers can be represented by an array of 2 floats.
+</p>
+
 <p>
 To facilitate the use in other languages than C, we provide some
 bindings in other languages in other repositories.
@@ -540,7 +549,7 @@ be implemented adapted to different problem sizes.
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/qmckl.html b/qmckl.html
index 06c829d..de212dc 100644
--- a/qmckl.html
+++ b/qmckl.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>QMCkl C header</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -247,7 +247,7 @@ header files.
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/qmckl_ao.html b/qmckl_ao.html
index a7f21c1..9f419e7 100644
--- a/qmckl_ao.html
+++ b/qmckl_ao.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>Atomic Orbitals</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -209,7 +209,18 @@ for the JavaScript code in this tag.
 </li>
 </ul>
 </li>
-<li><a href="#sec-2">2. <span class="todo TODO">TODO</span> Gaussian basis functions</a></li>
+<li><a href="#sec-2">2. Gaussian basis functions</a>
+<ul>
+<li><a href="#sec-2-1">2.1. <code>qmckl_ao_gaussians_vgl</code></a>
+<ul>
+<li><a href="#sec-2-1-1">2.1.1. Arguments</a></li>
+<li><a href="#sec-2-1-2">2.1.2. Requirements</a></li>
+<li><a href="#sec-2-1-3">2.1.3. Header</a></li>
+<li><a href="#sec-2-1-4">2.1.4. Source</a></li>
+</ul>
+</li>
+</ul>
+</li>
 <li><a href="#sec-3">3. <span class="todo TODO">TODO</span> Slater basis functions</a></li>
 </ul>
 </div>
@@ -400,6 +411,7 @@ end function qmckl_ao_powers_f
 </div>
 </div>
 
+
 <div id="outline-container-sec-1-2" class="outline-3">
 <h3 id="sec-1-2"><span class="section-number-3">1.2</span> <code>qmckl_ao_polynomial_vgl</code></h3>
 <div class="outline-text-3" id="text-1-2">
@@ -466,7 +478,7 @@ all polynomials with an angular momentum up to <code>lmax</code>.
 </tr>
 
 <tr>
-<td class="left"><code>VGL(ldv,n)</code></td>
+<td class="left"><code>VGL(ldv,5)</code></td>
 <td class="left">output</td>
 <td class="left">Value, gradients and Laplacian of the polynomials</td>
 </tr>
@@ -489,21 +501,21 @@ all polynomials with an angular momentum up to <code>lmax</code>.
 </li>
 <li><code>n</code> &gt; 0
 </li>
+<li><code>lmax</code> &gt;= 0
+</li>
+<li><code>ldl</code> &gt;= 3
+</li>
+<li><code>ldv</code> &gt;= (=lmax=+1)(=lmax=+2)(=lmax=+3)/6
+</li>
 <li><code>X</code> is allocated with at least \(3 \times 8\) bytes
 </li>
 <li><code>R</code> is allocated with at least \(3 \times 8\) bytes
 </li>
-<li><code>lmax</code> &gt;= 0
-</li>
-<li>On output, <code>n</code> should be equal to (=lmax=+1)(=lmax=+2)(=lmax=+3)/6
-</li>
 <li><code>L</code> is allocated with at least \(3 \times n \times 4\) bytes
 </li>
-<li><code>ldl</code> &gt;= 3
+<li><code>VGL</code> is allocated with at least \(n \times 5 \times 8\) bytes
 </li>
-<li><code>VGL</code> is allocated with at least \(5 \times n \times 8\) bytes
-</li>
-<li><code>ldv</code> &gt;= 5
+<li>On output, <code>n</code> should be equal to (=lmax=+1)(=lmax=+2)(=lmax=+3)/6
 </li>
 </ul>
 </div>
@@ -518,7 +530,7 @@ all polynomials with an angular momentum up to <code>lmax</code>.
 		const double *X, const double *R,
 		const int32_t lmax, const int64_t *n,
 		const int32_t *L,   const int64_t ldl,
-		const double *VGL,  const  int64_t ldv);
+		const double *VGL,  const int64_t ldv);
 </pre>
 </div>
 </div>
@@ -537,7 +549,7 @@ all polynomials with an angular momentum up to <code>lmax</code>.
   integer*8 , intent(out) :: n
   integer   , intent(out) :: L(ldl,(lmax+1)*(lmax+2)*(lmax+3)/6)
   integer*8 , intent(in)  :: ldl
-  real*8    , intent(out) :: VGL(ldv,(lmax+1)*(lmax+2)*(lmax+3)/6)
+  real*8    , intent(out) :: VGL(ldv,5)
   integer*8 , intent(in)  :: ldv
 
   integer*8         :: i,j
@@ -556,18 +568,21 @@ all polynomials with an angular momentum up to <code>lmax</code>.
      return
   endif
 
-  n = (lmax+1)*(lmax+2)*(lmax+3)/6
-
   if (ldl &lt; 3) then
      info = -2
      return
   endif
 
-  if (ldv &lt; 5) then
+  if (ldv &lt; (lmax+1)*(lmax+2)*(lmax+3)/6) then
      info = -3
      return
   endif
 
+  if (lmax &lt;= 0) then
+     info = -4
+     return
+  endif
+
 
   do i=1,3
      Y(i) = X(i) - R(i)
@@ -583,10 +598,10 @@ all polynomials with an angular momentum up to <code>lmax</code>.
   if (info /= 0) return
 
 
+  vgl(1,1) = 1.d0
+  vgl(1,2:5) = 0.d0
+  l(1:3,1) = 0
   n=1
-  vgl(1:5,1:n) = 0.d0
-  l(1:3,n) = 0
-  vgl(1,n) = 1.d0
   dd = 1.d0
   do d=1,lmax
      da = 0.d0
@@ -604,17 +619,17 @@ all polynomials with an angular momentum up to <code>lmax</code>.
 	   yz = pows(b,2) * pows(c,3)
 	   xz = pows(a,1) * pows(c,3)
 
-	   vgl(1,n) = xy * pows(c,3)
+	   vgl(n,1) = xy * pows(c,3)
 
 	   xy = dc * xy
 	   xz = db * xz
 	   yz = da * yz
 
-	   vgl(2,n) = pows(a-1,1) * yz
-	   vgl(3,n) = pows(b-1,2) * xz
-	   vgl(4,n) = pows(c-1,3) * xy
+	   vgl(n,2) = pows(a-1,1) * yz
+	   vgl(n,3) = pows(b-1,2) * xz
+	   vgl(n,4) = pows(c-1,3) * xy
 
-	   vgl(5,n) = &amp;
+	   vgl(n,5) = &amp;
 		(da-1.d0) * pows(a-2,1) * yz + &amp;
 		(db-1.d0) * pows(b-2,2) * xz + &amp;
 		(dc-1.d0) * pows(c-2,3) * xy
@@ -626,6 +641,13 @@ all polynomials with an angular momentum up to <code>lmax</code>.
      dd = dd + 1.d0
   end do
 
+  if (n /= (lmax+1)*(lmax+2)*(lmax+3)/6) then
+    info = -5
+    return
+  endif
+
+  info = 0
+
 end function qmckl_ao_polynomial_vgl_f
 </pre>
 </div>
@@ -636,15 +658,201 @@ end function qmckl_ao_polynomial_vgl_f
 
 
 <div id="outline-container-sec-2" class="outline-2">
-<h2 id="sec-2"><span class="section-number-2">2</span> <span class="todo TODO">TODO</span> Gaussian basis functions</h2>
+<h2 id="sec-2"><span class="section-number-2">2</span> Gaussian basis functions</h2>
+<div class="outline-text-2" id="text-2">
+</div><div id="outline-container-sec-2-1" class="outline-3">
+<h3 id="sec-2-1"><span class="section-number-3">2.1</span> <code>qmckl_ao_gaussians_vgl</code></h3>
+<div class="outline-text-3" id="text-2-1">
+<p>
+Computes the values, gradients and Laplacians at a given point of
+<code>n</code> Gaussian functions centered at the same point:
+</p>
+
+<p>
+\[ v_i = exp(-a_i |X-R|^2) \]
+\[ \nabla_x v_i = -2 a_i (X_x -  R_x) v_i \]
+\[ \nabla_y v_i = -2 a_i (X_y -  R_y) v_i \]
+\[ \nabla_z v_i = -2 a_i (X_z -  R_z) v_i \]
+\[ \Delta v_i = a_i (4 |X-R|^2 a_i - 6) v_i \]
+</p>
 </div>
 
+<div id="outline-container-sec-2-1-1" class="outline-4">
+<h4 id="sec-2-1-1"><span class="section-number-4">2.1.1</span> Arguments</h4>
+<div class="outline-text-4" id="text-2-1-1">
+<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
+
+
+<colgroup>
+<col  class="left" />
+
+<col  class="left" />
+
+<col  class="left" />
+</colgroup>
+<tbody>
+<tr>
+<td class="left"><code>context</code></td>
+<td class="left">input</td>
+<td class="left">Global state</td>
+</tr>
+
+<tr>
+<td class="left"><code>X(3)</code></td>
+<td class="left">input</td>
+<td class="left">Array containing the coordinates of the points</td>
+</tr>
+
+<tr>
+<td class="left"><code>R(3)</code></td>
+<td class="left">input</td>
+<td class="left">Array containing the x,y,z coordinates of the center</td>
+</tr>
+
+<tr>
+<td class="left"><code>n</code></td>
+<td class="left">input</td>
+<td class="left">Number of computed gaussians</td>
+</tr>
+
+<tr>
+<td class="left"><code>A(n)</code></td>
+<td class="left">input</td>
+<td class="left">Exponents of the Gaussians</td>
+</tr>
+
+<tr>
+<td class="left"><code>VGL(ldv,5)</code></td>
+<td class="left">output</td>
+<td class="left">Value, gradients and Laplacian of the Gaussians</td>
+</tr>
+
+<tr>
+<td class="left"><code>ldv</code></td>
+<td class="left">input</td>
+<td class="left">Leading dimension of array <code>VGL</code></td>
+</tr>
+</tbody>
+</table>
+</div>
+</div>
+
+<div id="outline-container-sec-2-1-2" class="outline-4">
+<h4 id="sec-2-1-2"><span class="section-number-4">2.1.2</span> Requirements</h4>
+<div class="outline-text-4" id="text-2-1-2">
+<ul class="org-ul">
+<li><code>context</code> is not 0
+</li>
+<li><code>n</code> &gt; 0
+</li>
+<li><code>ldv</code> &gt;= 5
+</li>
+<li><code>A(i)</code> &gt; 0 for all <code>i</code>
+</li>
+<li><code>X</code> is allocated with at least \(3 \times 8\) bytes
+</li>
+<li><code>R</code> is allocated with at least \(3 \times 8\) bytes
+</li>
+<li><code>A</code> is allocated with at least \(n \times 8\) bytes
+</li>
+<li><code>VGL</code> is allocated with at least \(n \times 5 \times 8\) bytes
+</li>
+</ul>
+</div>
+</div>
+
+<div id="outline-container-sec-2-1-3" class="outline-4">
+<h4 id="sec-2-1-3"><span class="section-number-4">2.1.3</span> Header</h4>
+<div class="outline-text-4" id="text-2-1-3">
+<div class="org-src-container">
+
+<pre class="src src-C">qmckl_exit_code qmckl_ao_gaussians_vgl(const qmckl_context context,
+		const double *X, const double *R,
+		const int64_t *n, const int64_t *A,
+		const double *VGL,  const int64_t ldv);
+</pre>
+</div>
+</div>
+</div>
+
+<div id="outline-container-sec-2-1-4" class="outline-4">
+<h4 id="sec-2-1-4"><span class="section-number-4">2.1.4</span> Source</h4>
+<div class="outline-text-4" id="text-2-1-4">
+<div class="org-src-container">
+
+<pre class="src src-f90">integer function qmckl_ao_gaussians_vgl_f(context, X, R, n, A, VGL, ldv) result(info)
+  implicit none
+  integer*8 , intent(in)  :: context
+  real*8    , intent(in)  :: X(3), R(3)
+  integer*8 , intent(in)  :: n
+  real*8    , intent(in)  :: A(n)
+  real*8    , intent(out) :: VGL(ldv,5)
+  integer*8 , intent(in)  :: ldv
+
+  integer*8         :: i,j
+  real*8            :: Y(3), r2, t, u, v
+
+  info = 0
+
+  if (context == 0_8) then
+     info = -1
+     return
+  endif
+
+  if (n &lt;= 0) then
+     info = -2
+     return
+  endif
+
+  if (ldv &lt; n) then
+     info = -3
+     return
+  endif
+
+
+  do i=1,3
+     Y(i) = X(i) - R(i)
+  end do
+  r2 = Y(1)*Y(1) + Y(2)*Y(2) + Y(3)*Y(3)
+
+  do i=1,n
+     VGL(i,1) = dexp(-A(i) * r2)
+  end do
+
+  do i=1,n
+     VGL(i,5) = A(i) * VGL(i,1)
+  end do
+
+  t = -2.d0 * ( X(1) - R(1) )
+  u = -2.d0 * ( X(2) - R(2) )
+  v = -2.d0 * ( X(3) - R(3) )
+
+  do i=1,n
+     VGL(i,2) = t * VGL(i,5)
+     VGL(i,3) = u * VGL(i,5)
+     VGL(i,4) = v * VGL(i,5)
+  end do
+
+  t = 4.d0 * r2
+  do i=1,n
+     VGL(i,5) = (t * A(i) - 6.d0) *  VGL(i,5)
+  end do
+
+end function qmckl_ao_gaussians_vgl_f
+</pre>
+</div>
+</div>
+</div>
+</div>
+</div>
+
+
 <div id="outline-container-sec-3" class="outline-2">
 <h2 id="sec-3"><span class="section-number-2">3</span> <span class="todo TODO">TODO</span> Slater basis functions</h2>
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/qmckl_context.html b/qmckl_context.html
index 763d376..45d50f9 100644
--- a/qmckl_context.html
+++ b/qmckl_context.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>Context</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -139,6 +139,48 @@ for the JavaScript code in this tag.
  }
 /*]]>*///-->
 </script>
+<script type="text/javascript" src="http://orgmode.org/mathjax/MathJax.js"></script>
+<script type="text/javascript">
+<!--/*--><![CDATA[/*><!--*/
+    MathJax.Hub.Config({
+        // Only one of the two following lines, depending on user settings
+        // First allows browser-native MathML display, second forces HTML/CSS
+        //  config: ["MMLorHTML.js"], jax: ["input/TeX"],
+            jax: ["input/TeX", "output/HTML-CSS"],
+        extensions: ["tex2jax.js","TeX/AMSmath.js","TeX/AMSsymbols.js",
+                     "TeX/noUndefined.js"],
+        tex2jax: {
+            inlineMath: [ ["\\(","\\)"] ],
+            displayMath: [ ['$$','$$'], ["\\[","\\]"], ["\\begin{displaymath}","\\end{displaymath}"] ],
+            skipTags: ["script","noscript","style","textarea","pre","code"],
+            ignoreClass: "tex2jax_ignore",
+            processEscapes: false,
+            processEnvironments: true,
+            preview: "TeX"
+        },
+        showProcessingMessages: true,
+        displayAlign: "center",
+        displayIndent: "2em",
+
+        "HTML-CSS": {
+             scale: 100,
+             availableFonts: ["STIX","TeX"],
+             preferredFont: "TeX",
+             webFont: "TeX",
+             imageFont: "TeX",
+             showMathMenu: true,
+        },
+        MMLorHTML: {
+             prefer: {
+                 MSIE:    "MML",
+                 Firefox: "MML",
+                 Opera:   "HTML",
+                 other:   "HTML"
+             }
+        }
+    });
+/*]]>*///-->
+</script>
 </head>
 <body>
 <div id="content">
@@ -164,24 +206,28 @@ for the JavaScript code in this tag.
 <ul>
 <li><a href="#sec-1-2-1">1.2.1. Header</a></li>
 <li><a href="#sec-1-2-2">1.2.2. Source</a></li>
+<li><a href="#sec-1-2-3">1.2.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-1-3">1.3. <code>qmckl_context_copy</code></a>
 <ul>
 <li><a href="#sec-1-3-1">1.3.1. Header</a></li>
 <li><a href="#sec-1-3-2">1.3.2. Source</a></li>
+<li><a href="#sec-1-3-3">1.3.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-1-4">1.4. <code>qmckl_context_previous</code></a>
 <ul>
 <li><a href="#sec-1-4-1">1.4.1. Header</a></li>
 <li><a href="#sec-1-4-2">1.4.2. Source</a></li>
+<li><a href="#sec-1-4-3">1.4.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-1-5">1.5. <code>qmckl_context_destroy</code></a>
 <ul>
 <li><a href="#sec-1-5-1">1.5.1. Header</a></li>
 <li><a href="#sec-1-5-2">1.5.2. Source</a></li>
+<li><a href="#sec-1-5-3">1.5.3. Fortran interface</a></li>
 </ul>
 </li>
 </ul>
@@ -192,36 +238,49 @@ for the JavaScript code in this tag.
 <ul>
 <li><a href="#sec-2-1-1">2.1.1. Header</a></li>
 <li><a href="#sec-2-1-2">2.1.2. Source</a></li>
+<li><a href="#sec-2-1-3">2.1.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-2-2">2.2. <code>qmckl_context_update_range</code></a>
 <ul>
 <li><a href="#sec-2-2-1">2.2.1. Header</a></li>
 <li><a href="#sec-2-2-2">2.2.2. Source</a></li>
+<li><a href="#sec-2-2-3">2.2.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-2-3">2.3. <code>qmckl_context_set_precision</code></a>
 <ul>
 <li><a href="#sec-2-3-1">2.3.1. Header</a></li>
 <li><a href="#sec-2-3-2">2.3.2. Source</a></li>
+<li><a href="#sec-2-3-3">2.3.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-2-4">2.4. <code>qmckl_context_set_range</code></a>
 <ul>
 <li><a href="#sec-2-4-1">2.4.1. Header</a></li>
 <li><a href="#sec-2-4-2">2.4.2. Source</a></li>
+<li><a href="#sec-2-4-3">2.4.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-2-5">2.5. <code>qmckl_context_get_precision</code></a>
 <ul>
 <li><a href="#sec-2-5-1">2.5.1. Header</a></li>
 <li><a href="#sec-2-5-2">2.5.2. Source</a></li>
+<li><a href="#sec-2-5-3">2.5.3. Fortran interface</a></li>
 </ul>
 </li>
 <li><a href="#sec-2-6">2.6. <code>qmckl_context_get_range</code></a>
 <ul>
 <li><a href="#sec-2-6-1">2.6.1. Header</a></li>
 <li><a href="#sec-2-6-2">2.6.2. Source</a></li>
+<li><a href="#sec-2-6-3">2.6.3. Fortran interface</a></li>
+</ul>
+</li>
+<li><a href="#sec-2-7">2.7. <code>qmckl_context_get_epsilon</code></a>
+<ul>
+<li><a href="#sec-2-7-1">2.7.1. Header</a></li>
+<li><a href="#sec-2-7-2">2.7.2. Source</a></li>
+<li><a href="#sec-2-7-3">2.7.3. Fortran interface</a></li>
 </ul>
 </li>
 </ul>
@@ -316,11 +375,11 @@ Returns the input <code>qmckl_context</code> if the context is valid, 0 otherwis
 <div class="org-src-container">
 
 <pre class="src src-C">qmckl_context qmckl_context_check(const qmckl_context context) {
-  qmckl_context_struct * ctx;
 
   if (context == (qmckl_context) 0) return (qmckl_context) 0;
 
-  ctx = (qmckl_context_struct*) context;
+  const qmckl_context_struct * ctx = (qmckl_context_struct*) context;
+
   if (ctx-&gt;tag != VALID_TAG) return (qmckl_context) 0;
 
   return context;
@@ -363,9 +422,8 @@ To create a new context, use <code>qmckl_context_create()</code>.
 
 <pre class="src src-C">qmckl_context qmckl_context_create() {
 
-  qmckl_context_struct*  context;
-
-  context = (qmckl_context_struct*) qmckl_malloc ((qmckl_context) 0, sizeof(qmckl_context_struct));
+  qmckl_context_struct* context =
+    (qmckl_context_struct*) qmckl_malloc ((qmckl_context) 0, sizeof(qmckl_context_struct));
   if (context == NULL) {
     return (qmckl_context) 0;
   }
@@ -381,6 +439,21 @@ To create a new context, use <code>qmckl_context_create()</code>.
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-1-2-3" class="outline-4">
+<h4 id="sec-1-2-3"><span class="section-number-4">1.2.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-1-2-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int64_t) function qmckl_context_create() bind(C)
+     use, intrinsic :: iso_c_binding
+   end function qmckl_context_create
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 
 <div id="outline-container-sec-1-3" class="outline-3">
@@ -418,23 +491,20 @@ for the new context
 
 <pre class="src src-C">qmckl_context qmckl_context_copy(const qmckl_context context) {
 
-  qmckl_context_struct* old_context;
-  qmckl_context_struct* new_context;
-  qmckl_context checked_context;
-
-  checked_context = qmckl_context_check(context);
+  const qmckl_context checked_context = qmckl_context_check(context);
 
   if (checked_context == (qmckl_context) 0) {
     return (qmckl_context) 0;
   }
 
-  new_context = (qmckl_context_struct*) qmckl_malloc (context, sizeof(qmckl_context_struct));
+  qmckl_context_struct* old_context = (qmckl_context_struct*) checked_context;
+
+  qmckl_context_struct* new_context = 
+    (qmckl_context_struct*) qmckl_malloc (context, sizeof(qmckl_context_struct));
   if (new_context == NULL) {
     return (qmckl_context) 0;
   }
 
-  old_context = (qmckl_context_struct*) checked_context;
-
   new_context-&gt;prev      = old_context;
   new_context-&gt;precision = old_context-&gt;precision;
   new_context-&gt;range     = old_context-&gt;range;
@@ -446,6 +516,22 @@ for the new context
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-1-3-3" class="outline-4">
+<h4 id="sec-1-3-3"><span class="section-number-4">1.3.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-1-3-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int64_t) function qmckl_context_copy(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_copy
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 
 <div id="outline-container-sec-1-4" class="outline-3">
@@ -482,21 +568,34 @@ Returns the previous context
 
 <pre class="src src-C">qmckl_context qmckl_context_previous(const qmckl_context context) {
 
-  qmckl_context checked_context;
-  qmckl_context_struct* ctx;
-
-  checked_context = qmckl_context_check(context);
+  const qmckl_context checked_context = qmckl_context_check(context);
   if (checked_context == (qmckl_context) 0) {
     return (qmckl_context) 0;
   }
 
-  ctx = (qmckl_context_struct*) checked_context;
+  const qmckl_context_struct* ctx = (qmckl_context_struct*) checked_context;
   return qmckl_context_check((qmckl_context) ctx-&gt;prev);
 }
 </pre>
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-1-4-3" class="outline-4">
+<h4 id="sec-1-4-3"><span class="section-number-4">1.4.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-1-4-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int64_t) function qmckl_context_previous(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_previous
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 
 <div id="outline-container-sec-1-5" class="outline-3">
@@ -533,15 +632,12 @@ Destroys the current context, leaving the ancestors untouched.
 <div class="outline-text-4" id="text-1-5-2">
 <div class="org-src-container">
 
-<pre class="src src-C">qmckl_exit_code qmckl_context_destroy(qmckl_context context) {
+<pre class="src src-C">qmckl_exit_code qmckl_context_destroy(const qmckl_context context) {
 
-  qmckl_context_struct* ctx;
-  qmckl_context checked_context;
-
-  checked_context = qmckl_context_check(context);
+  const qmckl_context checked_context = qmckl_context_check(context);
   if (checked_context == (qmckl_context) 0) return QMCKL_FAILURE;
 
-  ctx = (qmckl_context_struct*) context;
+  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
   if (ctx == NULL) return QMCKL_FAILURE;
 
   ctx-&gt;tag = INVALID_TAG;
@@ -552,6 +648,22 @@ Destroys the current context, leaving the ancestors untouched.
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-1-5-3" class="outline-4">
+<h4 id="sec-1-5-3"><span class="section-number-4">1.5.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-1-5-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_destroy(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_destroy
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 </div>
 
@@ -592,12 +704,11 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">qmckl_exit_code qmckl_context_update_precision(const qmckl_context context, const int precision) {
-  qmckl_context_struct* ctx;
 
   if (precision &lt;  2) return QMCKL_FAILURE;
   if (precision &gt; 53) return QMCKL_FAILURE;
 
-  ctx = (qmckl_context_struct*) context;
+  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
   if (ctx == NULL) return QMCKL_FAILURE;
 
   ctx-&gt;precision = precision;
@@ -607,6 +718,23 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-1-3" class="outline-4">
+<h4 id="sec-2-1-3"><span class="section-number-4">2.1.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-1-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_update_precision(context, precision) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+     integer (c_int32_t), intent(in), value :: precision
+   end function qmckl_context_update_precision
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 <div id="outline-container-sec-2-2" class="outline-3">
 <h3 id="sec-2-2"><span class="section-number-3">2.2</span> <code>qmckl_context_update_range</code></h3>
@@ -628,12 +756,11 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">qmckl_exit_code qmckl_context_update_range(const qmckl_context context, const int range) {
-  qmckl_context_struct* ctx;
 
   if (range &lt;  2) return QMCKL_FAILURE;
   if (range &gt; 11) return QMCKL_FAILURE;
 
-  ctx = (qmckl_context_struct*) context;
+  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
   if (ctx == NULL) return QMCKL_FAILURE;
 
   ctx-&gt;range = range;
@@ -643,6 +770,23 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-2-3" class="outline-4">
+<h4 id="sec-2-2-3"><span class="section-number-4">2.2.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-2-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_update_range(context, range) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+     integer (c_int32_t), intent(in), value :: range
+   end function qmckl_context_update_range
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 <div id="outline-container-sec-2-3" class="outline-3">
 <h3 id="sec-2-3"><span class="section-number-3">2.3</span> <code>qmckl_context_set_precision</code></h3>
@@ -664,9 +808,7 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">qmckl_context qmckl_context_set_precision(const qmckl_context context, const int precision) {
-  qmckl_context new_context;
-
-  new_context = qmckl_context_copy(context);
+  qmckl_context new_context = qmckl_context_copy(context);
   if (new_context == 0) return 0;
 
   if (qmckl_context_update_precision(context, precision) == QMCKL_FAILURE) return 0;
@@ -677,6 +819,23 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-3-3" class="outline-4">
+<h4 id="sec-2-3-3"><span class="section-number-4">2.3.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-3-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_set_precision(context, precision) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+     integer (c_int32_t), intent(in), value :: precision
+   end function qmckl_context_set_precision
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 <div id="outline-container-sec-2-4" class="outline-3">
 <h3 id="sec-2-4"><span class="section-number-3">2.4</span> <code>qmckl_context_set_range</code></h3>
@@ -698,9 +857,7 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">qmckl_context qmckl_context_set_range(const qmckl_context context, const int range) {
-  qmckl_context new_context;
-
-  new_context = qmckl_context_copy(context);
+  qmckl_context new_context = qmckl_context_copy(context);
   if (new_context == 0) return 0;
 
   if (qmckl_context_update_range(context, range) == QMCKL_FAILURE) return 0;
@@ -711,6 +868,23 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-4-3" class="outline-4">
+<h4 id="sec-2-4-3"><span class="section-number-4">2.4.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-4-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_set_range(context, range) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+     integer (c_int32_t), intent(in), value :: range
+   end function qmckl_context_set_range
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 
 <div id="outline-container-sec-2-5" class="outline-3">
@@ -721,7 +895,7 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="outline-text-4" id="text-2-5-1">
 <div class="org-src-container">
 
-<pre class="src src-C">int qmckl_context_get_precision(const qmckl_context context);
+<pre class="src src-C">int32_t qmckl_context_get_precision(const qmckl_context context);
 </pre>
 </div>
 </div>
@@ -733,14 +907,29 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">int qmckl_context_get_precision(const qmckl_context context) {
-  qmckl_context_struct* ctx;
-  ctx = (qmckl_context_struct*) context;
+  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
   return ctx-&gt;precision;
 }
 </pre>
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-5-3" class="outline-4">
+<h4 id="sec-2-5-3"><span class="section-number-4">2.5.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-5-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_get_precision(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_get_precision
+end interface
+</pre>
+</div>
+</div>
+</div>
 </div>
 <div id="outline-container-sec-2-6" class="outline-3">
 <h3 id="sec-2-6"><span class="section-number-3">2.6</span> <code>qmckl_context_get_range</code></h3>
@@ -750,7 +939,7 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="outline-text-4" id="text-2-6-1">
 <div class="org-src-container">
 
-<pre class="src src-C">int qmckl_context_get_range(const qmckl_context context);
+<pre class="src src-C">int32_t qmckl_context_get_range(const qmckl_context context);
 </pre>
 </div>
 </div>
@@ -762,17 +951,80 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 <div class="org-src-container">
 
 <pre class="src src-C">int qmckl_context_get_range(const qmckl_context context) {
-  qmckl_context_struct* ctx;
-  ctx = (qmckl_context_struct*) context;
+  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
   return ctx-&gt;range;
 }
 </pre>
 </div>
 </div>
 </div>
+
+<div id="outline-container-sec-2-6-3" class="outline-4">
+<h4 id="sec-2-6-3"><span class="section-number-4">2.6.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-6-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   integer (c_int32_t) function qmckl_context_get_range(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_get_range
+end interface
+</pre>
+</div>
+</div>
 </div>
 </div>
 
+<div id="outline-container-sec-2-7" class="outline-3">
+<h3 id="sec-2-7"><span class="section-number-3">2.7</span> <code>qmckl_context_get_epsilon</code></h3>
+<div class="outline-text-3" id="text-2-7">
+<p>
+Returns \(\epsilon = 2 / \log_{10} 2^{n-1}\) where <code>n</code> is the precision
+</p>
+</div>
+<div id="outline-container-sec-2-7-1" class="outline-4">
+<h4 id="sec-2-7-1"><span class="section-number-4">2.7.1</span> Header</h4>
+<div class="outline-text-4" id="text-2-7-1">
+<div class="org-src-container">
+
+<pre class="src src-C">double qmckl_context_get_epsilon(const qmckl_context context);
+</pre>
+</div>
+</div>
+</div>
+
+<div id="outline-container-sec-2-7-2" class="outline-4">
+<h4 id="sec-2-7-2"><span class="section-number-4">2.7.2</span> Source</h4>
+<div class="outline-text-4" id="text-2-7-2">
+<div class="org-src-container">
+
+<pre class="src src-C">double qmckl_context_get_epsilon(const qmckl_context context) {
+  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
+  return 1.0 / ((double) ((int64_t) 1 &lt;&lt; (ctx-&gt;precision-1)));
+}
+</pre>
+</div>
+</div>
+</div>
+
+<div id="outline-container-sec-2-7-3" class="outline-4">
+<h4 id="sec-2-7-3"><span class="section-number-4">2.7.3</span> Fortran interface</h4>
+<div class="outline-text-4" id="text-2-7-3">
+<div class="org-src-container">
+
+<pre class="src src-f90">interface
+   real (c_double) function qmckl_context_get_epsilon(context) bind(C)
+     use, intrinsic :: iso_c_binding
+     integer (c_int64_t), intent(in), value :: context
+   end function qmckl_context_get_epsilon
+end interface
+</pre>
+</div>
+</div>
+</div>
+</div>
+</div>
 
 <div id="outline-container-sec-3" class="outline-2">
 <h2 id="sec-3"><span class="section-number-2">3</span> Info about the molecular system</h2>
@@ -789,7 +1041,7 @@ The update functions return <code>QMCKL_SUCCESS</code> or <code>QMCKL_FAILURE</c
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/qmckl_distance.html b/qmckl_distance.html
index 0973899..91107ce 100644
--- a/qmckl_distance.html
+++ b/qmckl_distance.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>Computation of distances</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -515,7 +515,7 @@ end function qmckl_distance_sq_f
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/qmckl_memory.html b/qmckl_memory.html
index 5d1a79d..6e7638c 100644
--- a/qmckl_memory.html
+++ b/qmckl_memory.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>Memory management</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -244,7 +244,7 @@ Analogous of <code>malloc, but passing a context and a signed 64-bit integers as
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
diff --git a/test_qmckl.html b/test_qmckl.html
index 19268a1..92bfd3d 100644
--- a/test_qmckl.html
+++ b/test_qmckl.html
@@ -4,7 +4,7 @@
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 <head>
 <title>QMCkl test</title>
-<!-- 2020-10-31 Sat 18:09 -->
+<!-- 2020-11-04 Wed 23:47 -->
 <meta  http-equiv="Content-Type" content="text/html;charset=utf-8" />
 <meta  name="generator" content="Org-mode" />
 <style type="text/css">
@@ -229,7 +229,7 @@ int main(int argc, char* argv[MUNIT_ARRAY_PARAM(argc + 1)]) {
 </div>
 </div>
 <div id="postamble" class="status">
-<p class="date">Created: 2020-10-31 Sat 18:09</p>
+<p class="date">Created: 2020-11-04 Wed 23:47</p>
 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.2.2 (<a href="http://orgmode.org">Org</a> mode 8.2.10)</p>
 <p class="validation"><a href="http://validator.w3.org/check?uri=referer">Validate</a></p>
 </div>
