diff --git a/DS1-2015/E4.c b/DS1-2015/E4.c
index c32fa8d..61f295f 100644
--- a/DS1-2015/E4.c
+++ b/DS1-2015/E4.c
@@ -6,13 +6,13 @@
 
 // 1)
 
-float D3diag(int n, double* a, double* b, double* c) {
-    float D[n];
+double D3diag(int n, double* a, double* b, double* c) {
+    double D[n];
     int i;
     D[0] = b[0];
     D[1] = b[0] * b[1] - a[1] * c[0];
     for (i = 2; i < n; i++) {
-        D[i] = b[i] * D[i-1] - a[i] * c[i-2] * D[i-2];
+        D[i] = b[i] * D[i-1] - a[i] * c[i-1] * D[i-2];
     }
     return D[i];
 }
diff --git a/TP2/E4.c b/TP2/E4.c
index 5c2fdb9..dcf5c86 100644
--- a/TP2/E4.c
+++ b/TP2/E4.c
@@ -25,8 +25,10 @@ int main() {
     int X[N] = {2,8,-3,5,9,-4,-2,0,1,16};
     int DX[N][N];
     int i;
+    printf("-- X  ");
     afficherTableau(X, N);
     soustraire(X, DX[0], N);
+    printf("-- D1X");
     afficherTableau(DX[0], N-1);
     for (i = 0; i < N-1; i++) {
         soustraire(DX[i], DX[i+1], N-i);