with TableItem as (
           select To_Date('01.04.2011','dd.mm.yyyy') DAY, -5144.86 OKK from dual union all
           select To_Date('02.05.2011','dd.mm.yyyy') DAY,  1730.00 OKK from dual union all
           select To_Date('02.06.2011','dd.mm.yyyy') DAY,  1730.00 OKK from dual union all
           select To_Date('03.07.2011','dd.mm.yyyy') DAY,  1725.00 OKK from dual
)


 select round((1/x-1),7) F1
 from
 (
  select * from TableItem
   model 
        dimension by (Row_Number() over (order by DAY) NUM)
        measures (DAY-First_Value(DAY) over(order by DAY) dat,
                  OKK s,
                  0 ss,
                  0 f_a,
                  0 f_b,
                  0 f_x,
                  0 a,
                  1 b,
                  0 x,
                  0 iter
                 )
           rules  iterate(33)
           until (Abs(f_x[1])<Power(10,-7))
                 (ss[any]=s[CV()]*power(a[1],dat[CV()]/365),
                  f_a[1] =sum(ss)[any],
                  ss[any]=s[CV()]*power(b[1],dat[CV()]/365),
                   f_b[1]=sum(ss)[any],
                     x[1]=a[1]-f_a[1]*(b[1]-a[1])/(f_b[1]-f_a[1]),
                  ss[any]=s[CV()]*power(x[1],dat[CV()]/365),
                   f_x[1]=sum(ss)[any],
                     a[1]=decode(sign(f_a[1]*f_x[1]),1,x[1],a[1]),
                     b[1]=decode(sign(f_a[1]*f_x[1]),1,b[1],x[1]),
                  iter[1]=iteration_number+1
                 )
         )
 where NUM=1;