module hesapkitap
public::ikinciderece,ucuncuderece
contains
!******************************************
subroutine ikinciderece(a,b,c,x1,x2,delta)
real,intent(in)::a,b,c
real,intent(out)::x1,x2,delta
real::kok_delta
delta=b**2-4*a*c
if (delta>=0.0) then
kok_delta=sqrt(delta)
x1=(-b+kok_delta)/(2*a)
x2=(-b-kok_delta)/(2*a)
end if
end subroutine ikinciderece
!******************************************
function ucuncuderece(a,b,c,d) result(x1)
real,intent(in)::a,b,c,d
real::x1
real::fx,turevfx,xtemp,fark
real,parameter::minimum=1.0e-7
xtemp=1.0
do
turevfx=3*a*(xtemp**2)+2*b*xtemp+c
if (turevfx==0.0) then
xtemp=xtemp+1.0
turevfx=3*a*(xtemp**2)+2*b*xtemp+c
else
exit
end if
end do
do
fx=a*(xtemp**3)+b*(xtemp**2)+c*xtemp+d
turevfx=3*a*(xtemp**2)+2*b*xtemp+c
x1=xtemp-(fx/turevfx)
fark=abs(x1-xtemp)
if (fark<=minimum) then
x1=xtemp
exit
end if
xtemp=x1
end do
end function ucuncuderece
end module hesapkitap