14.3.12  Counting elements of a matrix which satisfy a given property

The count applies a function to the elements of a matrix or list and adds up the obtained values. In particular, if the function returns a boolean, then count returns the number of elements satifying the property that the function tests for.

• count takes two arguments:
  • f, a real-valued function.
  • A, a matrix or a list.
• count(f,A) returns the sum of the function f applied to the elements of A.

Examples

Indeed, 2+12+45+3+7+78=147.