diff --git a/fr/alnotz/Dual.java b/fr/alnotz/Dual.java
new file mode 100644
index 0000000..40c4aa1
--- /dev/null
+++ b/fr/alnotz/Dual.java
@@ -0,0 +1,49 @@
+package fr.alnotz;
+
+public class Dual implements IsDual{
+    private double r;
+    private double d;
+    public Dual(double r, double d){
+        this.r = r;
+        this.d = d;
+    }
+    public static Dual plus(IsDual dual0, IsDual dual1){
+        return new Dual(dual0.getR() + dual1.getR(), dual0.getD() + dual1.getD());
+    }
+    @Override
+    public double getR() {
+        return this.r;
+    }
+
+    @Override
+    public double getD() {
+        return this.d;
+    }
+
+    @Override
+    public void setR(double r) {
+        this.r = r;
+    }
+
+    @Override
+    public void setD(double d) {
+        this.d = d;
+    }
+
+    @Override
+    public void plus(IsDual dual) {
+        this.r += dual.getR();
+        this.d += dual.getD();
+    }
+
+    @Override
+    public void times(IsDual dual) {
+        this.r *= dual.getR();
+        this.d = 2 * this.r * dual.getD();
+    }
+
+    @Override
+    public boolean equals(IsDual dual) {
+        return this.r == dual.getR() && this.d == dual.getR();
+    }
+}
diff --git a/fr/alnotz/IsDual.java b/fr/alnotz/IsDual.java
new file mode 100644
index 0000000..221bd0e
--- /dev/null
+++ b/fr/alnotz/IsDual.java
@@ -0,0 +1,11 @@
+package fr.alnotz;
+
+public interface IsDual {
+    double getR();
+    double getD();
+    void setR(double r);
+    void setD(double d);
+    void plus(IsDual dual);
+    void times(IsDual dual);
+    boolean equals(IsDual dual);
+}