### 2.42.28 Count the elements equal to a given value : `count_eq`

`count_eq` takes as arguments: a real and a real list or
a real matrix.

`count_eq` returns the number of elements of the list or matrix
equal to the first argument.

Input :

`count_eq(12,[[2,12,45],[3,7,78]])`

Output :

`1`