diff --git a/C/opti.c b/C/opti.c
index 181f6fc8cf09e2c3d83f2ca235d276a3d9fbf64d..fb8f2f3178519f63ef7d3fc3bb64f60d7b08ffd2 100644
--- a/C/opti.c
+++ b/C/opti.c
@@ -90,6 +90,6 @@ couple deriver(double_vector_t* X, double_vector_t* Y){
 double erreur_quad(couple a, double_vector_t *X, double_vector_t *Y){
 	double somme = 0;
 	for (int i = 0; i < X->N; i++){
-		somme += (a.a * X->components[i] + a.b - Y->components[i])*(a.a * X->components[i] + a.b - Y->components[i]);
+		somme += pow((a.a * X->components[i] + a.b - Y->components[i]), 2);
 	}
 }
\ No newline at end of file