diff --git a/src/solveur/solveur.ts b/src/solveur/solveur.ts
index a04c81d40027f2d7988e2943e068747bae00a8fb..57ae45261a009853cd119965ccb03416dc0e9963 100644
--- a/src/solveur/solveur.ts
+++ b/src/solveur/solveur.ts
@@ -148,6 +148,10 @@ export class Solveur extends Nub implements Observer {
                         if (n.resultHasMultipleValues()) {
                             throw new Error("Solveur.update(): Nub to calculate must not have multiple values");
                         }
+                        // update Ytarget
+                        if (this.prms.Ytarget.singleValue === undefined) {
+                            this.prms.Ytarget.singleValue = this.nubToCalculate.calculatedParam.singleValue;
+                        }
                     }
                 }
                 if (data.name === "searchedParameter") {
diff --git a/src/solveur/solveur_params.ts b/src/solveur/solveur_params.ts
index dee786bd1e72e2a6d12ccf907f78e293b6b5659d..c4082f77a9cf924a015cb037dd6d8fcf9428956a 100644
--- a/src/solveur/solveur_params.ts
+++ b/src/solveur/solveur_params.ts
@@ -36,7 +36,7 @@ export class SolveurParams extends ParamsEquation implements IObservable {
         this._observable = new Observable();
         this._Xinit = new ParamDefinition(this, "Xinit", ParamDomainValue.ANY, undefined, rXinit);
         this._Ytarget = new ParamDefinition(this, "Ytarget", ParamDomainValue.ANY, undefined, rYtarget);
-        this._Y = new ParamDefinition(this, "Y", ParamDomainValue.ANY);
+        this._Y = new ParamDefinition(this, "Y", ParamDomainValue.ANY, undefined, undefined, undefined, false);
 
         this.addParamDefinition(this._Xinit);
         this.addParamDefinition(this._Ytarget);