diff --git a/src/learner.rs b/src/learner.rs
new file mode 100644
index 0000000..596c8cf
--- /dev/null
+++ b/src/learner.rs
@@ -0,0 +1,51 @@
+use crate::formula::Formula;
+
+pub struct Learner {
+    best_algorithm: Formula,
+    inputs: Vec<f64>,
+    expected_outputs: Vec<f64>,
+    formulas_per_iteration: usize,
+    iterations: usize,
+}
+
+impl Learner {
+    pub fn new(
+        inputs: Vec<f64>,
+        expected_outputs: Vec<f64>,
+        formulas_per_iteration: Option<usize>,
+        iterations: Option<usize>,
+    ) -> Self {
+        Self {
+            best_algorithm: Formula::new(),
+            inputs,
+            expected_outputs,
+            formulas_per_iteration: formulas_per_iteration.unwrap_or(200),
+            iterations: iterations.unwrap_or(200),
+        }
+    }
+    fn get_similarity(expected_output: Vec<f64>, real_output: Vec<f64>) -> Result<f64, ()> {
+        if expected_output.len() != real_output.len() {
+            return Err(());
+        }
+
+        let mut scalar = 0f64;
+        let mut expected_len = 0f64;
+        let mut real_len = 0f64;
+
+        for i in 0..expected_output.len() {
+            expected_len += expected_output[i] * expected_output[i];
+            real_len += real_output[i] * real_output[i];
+            scalar += expected_output[i] * real_output[i];
+        }
+
+        expected_len = expected_len.sqrt();
+        real_len = real_len.sqrt();
+
+        let cos: f64 = scalar / (expected_len * real_len);
+        let len_proportion: f64 = real_len / expected_len;
+        let similarity: f64 =
+            cos * (1f64 - ((len_proportion - 1f64).abs() / (len_proportion + 1f64)));
+
+        Ok(similarity)
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 97ffda3..76516c8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 pub mod formula;
+pub mod learner;
 pub mod node;
 
 #[cfg(test)]