diff --git a/src/learner.rs b/src/learner.rs
index c955bbc..9d2bac7 100644
--- a/src/learner.rs
+++ b/src/learner.rs
@@ -12,6 +12,7 @@ pub struct Learner {
     expected_outputs: Vec<f64>,
     formulas_per_iteration: usize,
     iterations: usize,
+    stop_epsilon: f64,
 }
 
 impl Learner {
@@ -20,6 +21,7 @@ impl Learner {
         expected_outputs: Vec<f64>,
         formulas_per_iteration: Option<usize>,
         iterations: Option<usize>,
+        stop_epsilon: Option<f64>,
     ) -> Self {
         Self {
             best_algorithm: Formula::new(),
@@ -27,6 +29,7 @@ impl Learner {
             expected_outputs,
             formulas_per_iteration: formulas_per_iteration.unwrap_or(200),
             iterations: iterations.unwrap_or(200),
+            stop_epsilon: stop_epsilon.unwrap_or(1e-8f64),
         }
     }
     pub fn calculate_formula(&mut self) -> Formula {
@@ -35,6 +38,10 @@ impl Learner {
                 &self.expected_outputs,
                 &self.best_algorithm.run(self.inputs.clone()),
             );
+            if 1. - current_best.unwrap_or(0.) <= self.stop_epsilon {
+                println!("employ");
+                break;
+            }
             let found_best = self.iterate();
             if found_best.1 > current_best.unwrap_or(0.) {
                 self.best_algorithm = found_best.0;
@@ -60,6 +67,9 @@ impl Learner {
             if found_best.1 > current_best.unwrap_or(0.) {
                 self.best_algorithm = found_best.0;
             }
+            if 1. - found_best.1 <= self.stop_epsilon {
+                break;
+            }
         }
         self.best_algorithm.clone()
     }
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..b3a92dd
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,27 @@
+use fapprox::learner::Learner;
+
+fn main() {
+    let mut learner = Learner::new(
+        vec![
+            0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11.0, 12., 13., 14., 15.,
+        ],
+        vec![
+            0.0, 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11.0, 12., 13., 14., 15.,
+        ]
+        .iter()
+        .map(|x: &f64| x.sin())
+        .map(|x| x + 1.)
+        .collect(),
+        Some(500),
+        Some(500),
+        None,
+    );
+    let formula = learner.calculate_formula();
+    formula.display_tree();
+    println!(
+        "{:?}",
+        formula.run(vec![
+            0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11.0, 12., 13., 14., 15.,
+        ])
+    )
+}