я что-то упустил в жизни?

#include <cmath>
#include <iostream>
int main(int argc, char** argv)
{
	std::cout << sin(M_PI/2) << '\n' << cos(M_PI/2) << '\n';
	return 0;
}

octave:1> cos(pi/2)
ans =  6.1230e-17
octave:2> eps
ans =  2.2204e-16
octave:3> help eps
`eps' is a built-in function
 -- Built-in Function:  eps
 -- Built-in Function:  eps (X)
 -- Built-in Function:  eps (N, M)
 -- Built-in Function:  eps (N, M, K, ...)
 -- Built-in Function:  eps (..., CLASS)
     Return a scalar, matrix or N-dimensional array whose elements are
     all eps, the machine precision.  More precisely, `eps' is the
     relative spacing between any two adjacent numbers in the machine's
     floating point system.  This number is obviously system dependent.
     On machines that support IEEE floating point arithmetic, `eps' is
     approximately 2.2204e-16 for double precision and 1.1921e-07 for
     single precision.
     When called with no arguments, return a scalar with the value
     `eps(1.0)'.  Given a single argument X, return the distance
     between X and the next largest value.  When called with more than
     one argument the first two arguments are taken as the number of
     rows and columns and any further arguments specify additional
     matrix dimensions.  The optional argument CLASS specifies the
     return type and may be either "double" or "single".

-->cos(%pi/2)
 ans  =
 
    6.123D-17