Reputation: 117
this is my first time trying to program in Fortran. I'm trying to write a program that prints the first 1476 terms of the Fibonacci sequence, then examines the first digit of each term and stores the number of 1s, 2s, 3s, ..., 9s that occur in an array.
The problem that I can't seem to figure out is how to read the first digit of each term. I've tried several things but am having difficulty with my limited knowledge of Fortran techniques. I write the terms to a text file and the idea is to read the first digit of each line and accumulate the respective number in the array. Does anyone have any suggestions of how to do this?
Here is my code so far:
(edit: I included the code I have for reading the file. Right now it just prints out 3.60772951994415996E-313, which seems like an address of some sort, because it's not one of the Fibonacci numbers. Also, it is the only thing printed, I expected that it would print out every line of the file...)
(edit edit: After considering this, perhaps there's a way to format the writing to the text file to just the first digit. Is there a way to set the number of significant digits of a real number to one? :P)
subroutine writeFib(n)
integer :: i
real*8 :: prev, current, newFib
prev = 0
current = 1
do i = 1, n
newFib = prev + current
prev = current
current = newFib
write(7,*) newFib
end do
return
end subroutine
subroutine recordFirstDigits(a)
integer :: openStat, inputStat
real*8 :: fibNum
open(7, file = "fort.7", iostat = openStat)
if (openStat > 0) stop "*** Cannot open the file ***"
do
read(7, *, iostat = inputStat) fibNum
print *,fibNum
if (inputStat > 0) stop "*** input error ***"
if (inputStat < 0) exit ! end of file
end do
close(7)
end subroutine
program test
integer :: k, a(9)
k = 1476
call writeFib(k)
call recordFirstDigits(a)
end program
Upvotes: 0
Views: 4216
Reputation: 2284
here are some hints:
floor(10^(frac(log_10(7214989861293412))))
Cheers, --Jared
Upvotes: 0
Reputation: 62528
Although the suggestions were in place, there were also several things that were forgotten. Range of the REAL kind, and some formatting problems.
Anyways, here's one patched up solution, compiled and working, so try to see if this will work for you. I've took the liberty of choosing my own method for fibonacci numbers calculation.
program SO1658805
implicit none
integer, parameter :: iwp = selected_real_kind(15,310)
real(iwp) :: fi, fib
integer :: i
character(60) :: line
character(1) :: digit
integer :: n0=0, n1=0, n2=0, n3=0, n4=0, n5=0, n6=0, n7=0, n8=0, n9=0
open(unit=1, file='temp.txt', status='replace')
rewind(1)
!-------- calculating fibonacci numbers -------
fi = (1+5**0.5)/2.
do i=0,1477
fib = (fi**i - (1-fi)**i)/5**0.5
write(1,*)fib,i
end do
!----------------------------------------------
rewind(1)
do i=0,1477
read(1,'(a)')line
line = adjustl(line)
write(*,'(a)')line
read(line,'(a1)')digit
if(digit.eq.' ') n0=n0+1
if(digit.eq.'1') n1=n1+1
if(digit.eq.'2') n2=n2+1
if(digit.eq.'3') n3=n3+1
if(digit.eq.'4') n4=n4+1
if(digit.eq.'5') n5=n5+1
if(digit.eq.'6') n6=n6+1
if(digit.eq.'7') n7=n7+1
if(digit.eq.'8') n8=n8+1
if(digit.eq.'9') n9=n9+1
end do
close(1)
write(*,'("Total number of different digits")')
write(*,'("Number of digits 0: ",i5)')n0
write(*,'("Number of digits 1: ",i5)')n1
write(*,'("Number of digits 2: ",i5)')n2
write(*,'("Number of digits 3: ",i5)')n3
write(*,'("Number of digits 4: ",i5)')n4
write(*,'("Number of digits 5: ",i5)')n5
write(*,'("Number of digits 6: ",i5)')n6
write(*,'("Number of digits 7: ",i5)')n7
write(*,'("Number of digits 8: ",i5)')n8
write(*,'("Number of digits 9: ",i5)')n9
read(*,*)
end program SO1658805
Aw, ... I just read you need the number of digits stored in to an array. While I just counted them.
Oh well, ... "left as an exercise for the reader ..." :-)
Upvotes: 1
Reputation: 8065
I wonder why the open statement succeeds when file 7 hasn't been closed. I think you need an endfile statement and/or a rewind statement in between writing and reading.
Paul Tomblin posted what you have to do after you solve your problem in getting reads to work in the first place.
Upvotes: 1
Reputation: 2692
I am getting an 'end of line' runtime error
You don't show the ! code to read here...
which makes it kind of difficult to guess what you are doing wrong :-)
Perhaps you need a loop to read each line and then jump out of the loop to a continue statement when there are no more lines.
Something like this:
do
read(7,*,end=10) fibNumber
end do
10 continue
Better still - look at the more modern style used in this revcomp program.
Upvotes: 0
Reputation: 182772
Can you read with a FORMAT(A1)? It's been 20 years so I don't remember the exact syntax.
Upvotes: 1