Update dot product

tutorials.md

@@ -43,7 +43,7 @@
         - Cos close to 0: orthogonal, not related
         - Cos close to -1: opposite
     - Calculation:
-      $Similarity(A,B) = cos(\theta) = \frac{A \dot B}{||A||\times||b||}$
+      $Similarity(A,B) = cos(\theta) = \frac{A \cdot B}{||A||\times||b||}$
         - $\theta$ is the angle between vectors
         - $A \dot B$ is the dot product, $A_1 B_1 + A_2 B_2 + ... + A_n B_n$
         - $||A||$ is the magnitude of vector,