integrate_body

program lab2
use integrate
implicit none
real(8)::a,b,eps,h,s=0,z=0
integer::i,method,n,k
byte::ok=0
interface !If a procedure has another procedure as dummy argument then one has to specify its type, just as the type of other parameters.
          !An interface block is used for this case. It consists of the procedure statement with the definitions of its arguments.
    real(8) function f(x)
    real(8) :: x
    end function f

end interface

print*, 'Input a,b,n,and eps'
read(*,*) a,b,n,eps
print*,'Choose method (1-left rect.,2-right,3-midpoint,4-trapezoidal,5-simpsons)'
read(*,*) method
do while (ok .EQ. 0)
    select case (method) !Выбор метода
        case (1)
            k=1
            call left(a,b,n,s,f)
            n=n*2
            call left(a,b,n,z,f)
        case (2)
            k=1
            call right(a,b,n,s,f)
            n=n*2
            call right(a,b,n,z,f)
        case (3)
            k=2
            call mid(a,b,n,s,f)
            n=n*2
            call mid(a,b,n,z,f)
        case (4)
            k=2
            call tr(a,b,n,s,f)
            n=n*2
            call tr(a,b,n,z,f)
        case (5)
            k=4
            call sim(a,b,n,s,f)
            n=n*2
            call sim(a,b,n,z,f)
        case default
            print*, 'Error'
        end select
    if (abs(z-s)/(2**k-1).LT.eps) then
        s=z
        ok=1
    end if
end do
print*, 'Results::'
print*, 'n=',n
print*, 'sum=',s
end program lab2

    function f(x)
    implicit none
    real(8)::f,x
    f=3*sin(x-4)-x**5+5
    end function f