- #1

Galizius

- 14

- 0

Here is my bisection code:

Fortran:

```
tl=3.0
tup=4.0
tempred=0.0
s=-0.234726128709272990292
do while (abs(total_calka) > eps)
tempred=(tl+tup)/2.0
beta=4.0/tempred
if (total_calka * s < 0) then
tup=tempred
else
tl=tempred
endif
call integration2
end do
```

And also there is necessary to explain what other things mean. Eps is the approximation; tl and tup are values of an interval where the root is placed in. S is the value of total_calka for the "tl" temperature value. The total_calka statement is a value which I am getting inside subroutine integration2. And here is the code for that.

Fortran:

```
module int2
use variables;
use fx; use int1
implicit none
contains
subroutine integration2
open(1,file='calka.dat', access='append')
total_calka=0.0
division=0.5
tot_old=10000.0
blad=10000.0
do while (blad>error)
irange=int(intrange/division)
total_calka=-(0.5**3)/3.0
do j=1,irange
r1=0.5+(j-1)*division
r2=r1+division
calka=0.0
do i=1,ngauss
integrand(i)=inte(x(i),beta,r2,r1)
calka=calka+integrand(i)*w(i)
enddo
total_calka=total_calka+calka*(r2-r1)
enddo
write(*,*) irange,division,tot_old,total_calka
division=division/2.0
blad=abs(tot_old-total_calka)
tot_old=total_calka
write(*,*) blad
enddo
write(1,*)tempred,-2*pi*total_calka
close(1)
end subroutine integration2
end module int2
```

There is also a function inte()

Code:

```
module fx
implicit none
contains
real(10) function inte(y,beta,r2,r1)
real(kind=10)::r,beta,r6,r2,r1,u,y
r=(r2-r1)*y+r1
r6=(1.0/r)**6
u=beta*r6*(r6-1.0d0)
if (u>100.d0) then
inte=-1.0d0
else
inte=exp(-u)-1.d0
endif
inte=r*r*inte
end function inte
end module fx
```

I don't know why it's not getting me a value of the root, while when I was doing a simple loop for temperature interval 0.1<T<5.0 I was getting the values of every total_calka for each temperature. I would be grateful for any hints that are helpful.