# Blocking math [Obj,Int]

### Description
Executes a free math expression on the values of the second column, for matching objects (according to the `PAIRS` input).

Warning: this block can fail if the expression is invalid (e.g. referring to a non available mathematical function),
or if the expressions computes to invalid results (e.g. division by zero).

### Input
- `A [OBJ,INTEGER]`: a list of pairs
- `PAIRS`: Pairs of `A` (first column) and `B` (second column) objects for which to compute the expression
- `B [OBJ,INTEGER]`: a list of pairs

### Output
- `RESA [OBJ,INTEGER]`: result of the operation, with matching objects from `A`
- `RESB [OBJ,INTEGER]`: result of the operation, with matching objects from `B`

### Parameters
- `Expression`: the mathematical expression to compute
  - use `$A` and `$B` to refer to the values comings from inputs `A` and `B`
  - arithmetic operators and common mathematical functions can be used
  - the expression is evaluated by the database engine. See [MonetDB Functions and Operators](https://www.monetdb.org/Documentation/SQLReference/FunctionsAndOperators/MathematicalFunctionsOperators) for a full list of functions and operators available.