diff --git a/fr/alnotz/DualQuaternion.java b/fr/alnotz/DualQuaternion.java
new file mode 100644
index 0000000..dce811e
--- /dev/null
+++ b/fr/alnotz/DualQuaternion.java
@@ -0,0 +1,273 @@
+package fr.alnotz;
+
+public class DualQuaternion implements IsDualQuaternion {
+    private double rs;
+    private double ri;
+    private double rj;
+    private double rk;
+    private double ds;
+    private double di;
+    private double dj;
+    private double dk;
+    public DualQuaternion(){
+        this.rs = 0;
+        this.ri = 0;
+        this.rj = 0;
+        this.rk = 0;
+        this.ds = 0;
+        this.di = 0;
+        this.dj = 0;
+        this.dk = 0;
+    }
+    public DualQuaternion(Quaternion quaternion0, Quaternion quaternion1){
+        this.rs = quaternion0.getS();
+        this.ri = quaternion0.getI();
+        this.rj = quaternion0.getJ();
+        this.rk = quaternion0.getK();
+        this.ds = quaternion1.getS();
+        this.di = quaternion1.getI();
+        this.dj = quaternion1.getJ();
+        this.dk = quaternion1.getK();
+    }
+    public DualQuaternion(IsDual dual0, IsDual dual1, IsDual dual2, IsDual dual3){
+        this.rs = dual0.getR();
+        this.ri = dual1.getR();
+        this.rj = dual2.getR();
+        this.rk = dual3.getR();
+        this.ds = dual0.getD();
+        this.di = dual1.getD();
+        this.dj = dual2.getD();
+        this.dk = dual3.getD();
+    }
+    public DualQuaternion(double rs, double ri, double rj, double rk, double ds, double di, double dj, double dk){
+        this.rs = rs;
+        this.ri = ri;
+        this.rj = rj;
+        this.rk = rk;
+        this.ds = ds;
+        this.di = di;
+        this.dj = dj;
+        this.dk = dk;
+    }
+    @Override
+    public IsQuaternion getR() {
+        return new Quaternion(this.rs, this.ri, this.rj, this.rk);
+    }
+
+    @Override
+    public IsQuaternion getD() {
+        return new Quaternion(this.ds, this.di, this.dj, this.dk);
+    }
+
+    @Override
+    public IsDual getS() {
+        return new Dual(this.rs, this.ds);
+    }
+
+    @Override
+    public IsDual getI() {
+        return new Dual(this.ri, this.di);
+    }
+
+    @Override
+    public IsDual getJ() {
+        return new Dual(this.rj, this.dj);
+    }
+
+    @Override
+    public IsDual getK() {
+        return new Dual(this.rk, this.dk);
+    }
+
+    @Override
+    public void setR(IsQuaternion quaternion) {
+        this.rs = quaternion.getS();
+        this.ri = quaternion.getI();
+        this.rj = quaternion.getJ();
+        this.rk = quaternion.getK();
+    }
+
+    @Override
+    public void setD(IsQuaternion quaternion) {
+        this.ds = quaternion.getS();
+        this.di = quaternion.getI();
+        this.dj = quaternion.getJ();
+        this.dk = quaternion.getK();
+    }
+
+    @Override
+    public void setS(IsDual dual) {
+        this.rs = dual.getR();
+        this.ds = dual.getD();
+
+    }
+
+    @Override
+    public void setI(IsDual dual) {
+        this.ri = dual.getR();
+        this.di = dual.getD();
+    }
+
+    @Override
+    public void setJ(IsDual dual) {
+        this.rj = dual.getR();
+        this.dj = dual.getD();
+    }
+
+    @Override
+    public void setK(IsDual dual) {
+        this.rk = dual.getR();
+        this.dk = dual.getD();
+    }
+    @Override
+    public double getRS() {
+        return rs;
+    }
+
+    @Override
+    public void setRS(double rs) {
+        this.rs = rs;
+    }
+
+    @Override
+    public double getRI() {
+        return ri;
+    }
+
+    @Override
+    public void setRI(double ri) {
+        this.ri = ri;
+    }
+
+    @Override
+    public double getRJ() {
+        return rj;
+    }
+
+    @Override
+    public void setRJ(double rj) {
+        this.rj = rj;
+    }
+
+    @Override
+    public double getRK() {
+        return rk;
+    }
+
+    @Override
+    public void setRK(double rk) {
+        this.rk = rk;
+    }
+
+    @Override
+    public double getDS() {
+        return ds;
+    }
+
+    @Override
+    public void setDS(double ds) {
+        this.ds = ds;
+    }
+
+    @Override
+    public double getDI() {
+        return di;
+    }
+
+    @Override
+    public void setDI(double di) {
+        this.di = di;
+    }
+
+    @Override
+    public double getDJ() {
+        return dj;
+    }
+
+    @Override
+    public void setDJ(double dj) {
+        this.dj = dj;
+    }
+
+    @Override
+    public double getDK() {
+        return dk;
+    }
+
+    @Override
+    public void setDK(double dk) {
+        this.dk = dk;
+    }
+
+    @Override
+    public IsDualQuaternion plus(IsDualQuaternion dualQuaternion) {
+        return new DualQuaternion(this.rs + dualQuaternion.getRS(),
+                this.ri + dualQuaternion.getRI(),
+                this.rj + dualQuaternion.getRJ(),
+                this.rk + dualQuaternion.getRK(),
+                this.ds + dualQuaternion.getDS(),
+                this.dk + dualQuaternion.getDI(),
+                this.dj + dualQuaternion.getDJ(),
+                this.dk + dualQuaternion.getDK()) {
+        };
+    }
+
+    @Override
+    public IsDualQuaternion times(IsDualQuaternion dualQuaternion) {
+        /*
+         * (a0 + b0i + c0j + d0k)(a1 + b1i + c1j + d1k)
+         * (a0a1 - b0b1 - c0c1 - d0d1) +
+         *   (a0b1 + b0a1 + c0d1 - d0c1)i +
+         *   (a0c1 - b0d1 + c0a1 + d0b1)j +
+         *   (a0d1 + b0c1 - c0b1 + d0a1)k
+         * a0b1 = R(a0)R(b1) + R(a0)D(b1)epsilon + D(a0)R(b1)epsilon
+         */
+        double newRS = this.rs * dualQuaternion.getRS() -
+                this.ri * dualQuaternion.getRI() -
+                this.rj * dualQuaternion.getRJ() -
+                this.rk * dualQuaternion.getRK();
+        double newRI = this.rs * dualQuaternion.getRI() +
+                this.ri * dualQuaternion.getRK() +
+                this.rj * dualQuaternion.getRS() -
+                this.rk * dualQuaternion.getRJ();
+        double newRJ = this.rs * dualQuaternion.getRJ() -
+                this.ri * dualQuaternion.getRK() +
+                this.rj * dualQuaternion.getRS() +
+                this.rk * dualQuaternion.getRI();
+        double newRK = this.rs * dualQuaternion.getRK() +
+                this.ri * dualQuaternion.getRJ() -
+                this.rj * dualQuaternion.getRI() +
+                this.rk * dualQuaternion.getRS();
+        double newDS = this.rs * dualQuaternion.getDS() + this.ds * dualQuaternion.getRS() -
+                this.ri * dualQuaternion.getDI() - this.di * dualQuaternion.getRI() -
+                this.rj * dualQuaternion.getDJ() - this.dj * dualQuaternion.getRJ() -
+                this.rk * dualQuaternion.getDK() - this.dk * dualQuaternion.getRK();
+        double newDI = this.rs * dualQuaternion.getDI() + this.ds * dualQuaternion.getRI() +
+                this.ri * dualQuaternion.getDK() + this.di * dualQuaternion.getRK() +
+                this.rj * dualQuaternion.getDS() + this.dj * dualQuaternion.getRS() -
+                this.rk * dualQuaternion.getDJ() - this.dk * dualQuaternion.getRJ();
+        double newDJ = this.rs * dualQuaternion.getDJ() + this.ds * dualQuaternion.getRJ() -
+                this.ri * dualQuaternion.getDK() - this.di * dualQuaternion.getRK() +
+                this.rj * dualQuaternion.getDS() + this.dj * dualQuaternion.getRS() +
+                this.rk * dualQuaternion.getDI() + this.dk * dualQuaternion.getRI();
+        double newDK = this.rs * dualQuaternion.getDK() + this.ds * dualQuaternion.getRK() +
+                this.ri * dualQuaternion.getDJ() + this.di * dualQuaternion.getRJ() -
+                this.rj * dualQuaternion.getDI() - this.dj * dualQuaternion.getRI() +
+                this.rk * dualQuaternion.getDS() + this.dk * dualQuaternion.getRS();
+        IsDualQuaternion newDQ = new DualQuaternion(newRS, newRI, newRJ, newRK,
+                newDS, newDI, newDJ, newDK);
+        return newDQ;
+    }
+
+    @Override
+    public boolean equals(IsDualQuaternion dualQuaternion) {
+        return this.rs == dualQuaternion.getRS() &&
+        this.ri == dualQuaternion.getRI() &&
+        this.rj == dualQuaternion.getRJ() &&
+        this.rk == dualQuaternion.getRK() &&
+        this.ds == dualQuaternion.getDS() &&
+        this.di == dualQuaternion.getDI() &&
+        this.dj == dualQuaternion.getDJ() &&
+        this.dk == dualQuaternion.getDK();
+    }
+}
diff --git a/fr/alnotz/IsDualQuaternion.java b/fr/alnotz/IsDualQuaternion.java
index f589174..2b58437 100644
--- a/fr/alnotz/IsDualQuaternion.java
+++ b/fr/alnotz/IsDualQuaternion.java
@@ -1,5 +1,35 @@
 package fr.alnotz;
 
 public interface IsDualQuaternion {
-    /*…*/
+    IsQuaternion getR();
+    IsQuaternion getD();
+    IsDual getS();
+    IsDual getI();
+    IsDual getJ();
+    IsDual getK();
+    double getRS();
+    double getRI();
+    double getRJ();
+    double getRK();
+    double getDS();
+    double getDI();
+    double getDJ();
+    double getDK();
+    void setR(IsQuaternion quaternion);
+    void setD(IsQuaternion quaternion);
+    void setS(IsDual dual);
+    void setI(IsDual dual);
+    void setJ(IsDual dual);
+    void setK(IsDual dual);
+    void setRS(double rs);
+    void setRI(double ri);
+    void setRJ(double rj);
+    void setRK(double rk);
+    void setDS(double ds);
+    void setDI(double di);
+    void setDJ(double dj);
+    void setDK(double dk);
+    IsDualQuaternion plus(IsDualQuaternion dualQuaternion);
+    IsDualQuaternion times(IsDualQuaternion dualQuaternion);
+    boolean equals(IsDualQuaternion dualQuaternion);
 }