module funciones
implicit none

real, parameter :: PI = 4 * atan (1.)

contains

	real function f(x)
	real, intent (in) :: x

		if (x <= -(PI/2)) then

			f = -1

		if (x < PI/2) then

			f = cos (x)

		else

			 f = 0

		end if

	end function

end module

program Hito5integral

use funciones

implicit none

	real, allocatable :: x(:) , y(:)
	real :: a, b, dx
	integer :: N, i 

	a = -2 * PI

	b = PI

	N = 10

	dx = (b-a)/N

	x = [(a + i * dx , i = 0 , N)]

		do i = 0 , N

			y(i) = F (x(i))

		end do

	write (*,*) 'Suma=' , dx * sum (y)

end program