count takes as argument : a real function f and a list
l of length n (or a matrix A of dimension p*q).
count applies the function to the list (or matrix) elements and returns
their sum, i.e. :
count(f,l) returns f(l[0])+f(l[1])+...+f(l[n-1]) or
count(f,A) returns f(A[0,0])+....+f(A[p-1,q-1]).
If f is a boolean function count returns the number of elements
of the list (or of the matrix) for which the boolean function is true.
Input :
Output :
because : 2+12+45+3+7+78=147.
Input :
Output :
Input :
Output :
Input :
Output :
Input :
^
2,[3,5,1])Output :
Indeed 32+52+11=35.
Input :
Output :
Indeed, id is the identity functions and 3+5+1=9.
Input :
Output :
Indeed, 1 is the constant function equal to 1 and 1+1+1=3.