A perfect number is a positive integer that is equal to the sum of its positive divisors other than itself. Thus 6 is a perfect number because it has divisors 1, 2 and 3, the sum of which is 6.
There are actually very few perfect numbers in any given range, so rather than waste precious CPU cycles determining the divisors of a number and then summing them to see if it is perfect or not (most of the time it won't be) it is much easier and quicker to simply store them in a static array.
A 64-bit unsigned integer can store values in the range 0 to 18,446,744,073,709,551,615, but there are only 8 perfect numbers in this range. Thus the following array will suffice:
unsigned long long perfect = {6, 28, 496, 8128, 33550336, 8589869056, 137438691328, 2305843008139952128 };
To determine if a given positive value is perfect or not, simply test to see if it exists in this array. The following function shows how this can be achieved.
bool is_perfect(const unsigned long long value)
{
const unsigned long long perfect[8] = {6, 28, 496, 8128, 33550336, 8589869056, 137438691328, 2305843008139952128};
for(unsigned i=0; i<8; ++i)
if(value==perfect[i])
return true;
return false;
}
The 2nd function of the log button is the inverse log. Press 2nd log, which displays 10^( on the screen. Put a number after the opening parenthesis.
That is not a function, although it does involve the function of addition. A function is something that is done to numbers.
...a function call.
There is no such term as "building function" in C++.
printf ("x")
Control is returning to the caller of the function.
yes,we can make function inline
The given quadratic expression can not be factored as a perfect square.
There is no known function for the mass number and atomic number. However, the difference between these two values gives the number of neutrons present in that atom.
No. x2+5x is a polynomial, an algebraic expression or a formula, but it is not a function. It could be used to help define a function. {(x,y) | y = x2 + 5x , x any real number} is a function
It is the first function that gets called when the program is executed.
There is no such thing. You probably meant the main function. The main function is the only function that is required as it serves as the entry point of the program.