diff --git a/elections/migrations/0016_auto_20210329_1759.py b/elections/migrations/0016_auto_20210329_1759.py
new file mode 100644
index 0000000..5b9ce64
--- /dev/null
+++ b/elections/migrations/0016_auto_20210329_1759.py
@@ -0,0 +1,69 @@
+# Generated by Django 2.2.19 on 2021-03-29 15:59
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("elections", "0015_condorcet"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Duel",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                (
+                    "amount",
+                    models.PositiveSmallIntegerField(
+                        verbose_name="votes supplémentaires"
+                    ),
+                ),
+                (
+                    "loser",
+                    models.OneToOneField(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="contests_lost",
+                        to="elections.Option",
+                    ),
+                ),
+                (
+                    "question",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="duels",
+                        to="elections.Question",
+                    ),
+                ),
+                (
+                    "winner",
+                    models.OneToOneField(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="contests_won",
+                        to="elections.Option",
+                    ),
+                ),
+            ],
+        ),
+        migrations.AlterModelOptions(
+            name="rank",
+            options={"ordering": ["vote"]},
+        ),
+        migrations.AlterModelOptions(
+            name="vote",
+            options={"ordering": ["option"]},
+        ),
+        migrations.DeleteModel(
+            name="Matrix",
+        ),
+    ]
diff --git a/elections/migrations/0017_auto_20210329_1802.py b/elections/migrations/0017_auto_20210329_1802.py
new file mode 100644
index 0000000..e28d94a
--- /dev/null
+++ b/elections/migrations/0017_auto_20210329_1802.py
@@ -0,0 +1,32 @@
+# Generated by Django 2.2.19 on 2021-03-29 16:02
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("elections", "0016_auto_20210329_1759"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="duel",
+            name="loser",
+            field=models.ForeignKey(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="contests_lost",
+                to="elections.Option",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="duel",
+            name="winner",
+            field=models.ForeignKey(
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="contests_won",
+                to="elections.Option",
+            ),
+        ),
+    ]
diff --git a/elections/models.py b/elections/models.py
index 8e0f45f..4419eaa 100644
--- a/elections/models.py
+++ b/elections/models.py
@@ -123,17 +123,26 @@ class Vote(models.Model):
     option = models.ForeignKey(Option, on_delete=models.CASCADE)
     user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
 
+    class Meta:
+        ordering = ["option"]
+
 
 class Rank(models.Model):
     vote = models.OneToOneField(Vote, on_delete=models.CASCADE)
     rank = models.PositiveSmallIntegerField(_("rang de l'option"))
 
+    class Meta:
+        ordering = ["vote"]
 
-class Matrix(models.Model):
-    winner = models.OneToOneField(
+
+class Duel(models.Model):
+    question = models.ForeignKey(
+        Question, related_name="duels", on_delete=models.CASCADE
+    )
+    winner = models.ForeignKey(
         Option, related_name="contests_won", on_delete=models.CASCADE
     )
-    loser = models.OneToOneField(
+    loser = models.ForeignKey(
         Option, related_name="contests_lost", on_delete=models.CASCADE
     )
     amount = models.PositiveSmallIntegerField(_("votes supplémentaires"))
diff --git a/elections/utils.py b/elections/utils.py
index 6e3e9f4..1c8ad60 100644
--- a/elections/utils.py
+++ b/elections/utils.py
@@ -2,6 +2,8 @@ import csv
 import io
 import random
 
+import numpy as np
+
 from django.contrib.auth.hashers import make_password
 from django.core.exceptions import ValidationError
 from django.core.mail import EmailMessage, get_connection
@@ -87,6 +89,53 @@ class TallyFunctions:
 
         Option.objects.bulk_update(options, ["nb_votes"])
 
+    def tally_rank(question):
+        """On dépouille un vote par classement et on crée la matrice des duels"""
+        from .models import Duel, Rank
+
+        def duel(a, b):
+            # Renvoie 1 si a est classé avant b, -1 si c'est l'inverse et
+            # 0 si a et b ont le même rang, ce qui permet d'avoir directement
+            # le graphe des duels en faisant le max avec la matrice nulle
+            return (a.rank < b.rank) - (a.rank > b.rank)
+
+        options = list(question.options.all())
+        ranks = Rank.objects.select_related("vote").filter(vote__option__in=options)
+        ranks_by_user = {}
+
+        for r in ranks:
+            user = r.vote.user
+            if user in ranks_by_user:
+                ranks_by_user[user].append(r)
+            else:
+                ranks_by_user[user] = [r]
+
+        ballots = []
+
+        # Pour chaque votant·e, on regarde son classement
+        for user in ranks_by_user:
+            votes = ranks_by_user[user]
+            ballots.append(np.array([[duel(x, y) for x in votes] for y in votes]))
+
+        # On additionne les classements de tout le monde
+        duels = np.maximum(sum(ballots), 0)
+
+        cells = []
+
+        # On enregistre la matrice
+        for i, line in enumerate(duels):
+            for j, cell in enumerate(line):
+                if cell > 0:
+                    cells.append(
+                        Duel(
+                            question=question,
+                            winner=options[j],
+                            loser=options[i],
+                            amount=cell,
+                        )
+                    )
+        Duel.objects.bulk_create(cells)
+
 
 class ValidateFunctions:
     """Classe pour valider les formsets selon le type de question"""