# Expressions

This section explains the types and meanings of expressions, which are the core section of this product, they let you implement infinite kinds of strategies. In the expression fields, you write mathematical and calculation logic. For example, if you have two moving average indicators and you want to ask the expert when the first one is greater than the second one, then something should be done, you should write in the expression field “MA1>MA2”. The expert has an internal engine that can interpret these kinds of expressions and use the results.

There are two kinds of expressions in mathematics: Logical and Numerical.

Logical expressions are those that have a true or false result and can be a combination of complex logical expressions. For example, if “X>12 AND Y-3<8”.

Numerical expressions are those that return a number as the result. This is an example of numerical expression:   (X-2)  * (log(2)-6) + Sin(2π)

that could be written like this:

(X-2)*MathExp * (MathLog – 6) + MathSin[2*pi]

ESB supports three kinds of expressions: Logical, Functional and Conditional/If Expressions