c:	camfill.for
c:
c:	Converted from CAMFILL.BAS basic program.
c:
c:	! Computes "SUB" locations during CAMERA tows by interpolating
c:	! between known positions throughout the record.  Data which
c:	! results is aproximate position for every second
c:	!
c:	!    ***NOTE*** this program must be compiles usuing 
c:	!		$bas/double camfill
c:	! 
c:	! Modified for 1988 VENTS navigation data where the tow data were
c:	! by Dan Clapp from Newport as output from his navigation routines
c:	! where the camera was within the AT-NAV grid, or from the 
c:	! INTELLIFISH program where the fish was outside the AT-NAV grid.
c:	! Resulting positions at each second are in
c:	! latitude and longitude (xx.xxxxx degrees) and distance along
c:	! tow is calculated from position converted to meters using
c:	!		1 degree latitude = 111,120 meters
c:	!		1 degree long = meters from the folowing fit
c:	!		 m/deg = -12.057143*L**2 -280.577143*L + 115890.342857
c:	!
c:	!  S.Walker : March 1989


	character*40 sub_file,newpos_file
	character*80 dlin1,dlin2

	integer*4 aveint
	integer*4 hr1,hr2, min1,min2, sec1,sec2
	integer*4 latdeg1,latdeg2, londeg1,londeg2
	integer*4 hrs,mins,secs

	real*8 xx(0:31000),yy(0:31000),stim(0:31000)
	real*8 x(0:31000),y(0:31000)
	real*8 xint,yint,dx,dy,dist,cumdist,fct
	real*8 x1,y1,x2,y2
	real*8 latmin1,latmin2,lonmin1,lonmin2



  100	write (6,101)
  101	format (' Enter SUB position file name: '$)
	read (5,102)  sub_file
  102	format (a)

	write (6,121)
  121	format (' Enter time interval used for averaging: '$)
	read (5,122)  aveint
  122	format (i10)

	write (6,141)
  141	format (' Enter file name for extrapolated positions: '$)
	read (5,142)  newpos_file
  142	format (a)

	open (unit=1,name=sub_file,type='old',access='sequential',
	1     carriagecontrol='list')

	open (unit=2,name=newpos_file,type='new',access='sequential',
	1     carriagecontrol='list')


	j = 0

	read (1,161,end=900)  dlin1
  161	format (a)

  200	read (1,201,end=900)  dlin2
  201	format (a)

	decode (36,221,dlin1)  hr1,min1,sec1,
	1                      latdeg1,latmin1,
	1                      londeg1,lonmin1
  221	format (5x,i2,i3,i3,i4,f7.3,1x,i4,f7.3)

	decode (36,221,dlin2)  hr2,min2,sec2,
	1                      latdeg2,latmin2,
	1                      londeg2,lonmin2

	y1 = latdeg1 + (latmin1/60.0)
	y2 = latdeg2 + (latmin2/60.0)
	x1 = londeg1 + (lonmin1/60.0)
	x2 = londeg2 + (lonmin2/60.0)

	time1 = sec1 + (60*min1) + ((60*hr1)*60)
	time2 = sec2 + (60*min2) + ((60*hr2)*60)
	t2adj = sec2 + (60*min2) + ((60*24)*60)

c:	timeint is time difference from previous in seconds

	if ( time2 .lt. time1 )  timeint = (t2adj-time1)
	if ( time2 .gt. time1 )  timeint = (time2-time1)

	xint = abs((x1-x2)/timeint)
	yint = abs((y1-y2)/timeint)

	if ( x1 .gt. x2 )  xint = -xint
	if ( y1 .gt. y2 )  yint = -yint
   
	do i = 0, timeint
	   xx(i) = x1 + (xint*i)
	   yy(i) = y1 + (yint*i)
	   stim(i) = time1 + i 
	end do


	do i = 0, timeint-1

	   hrs    = aint((stim(i)/60.0)/60.0)
	   hrsec  = hrs*60*60
	   rems   = stim(i) - hrsec
	   mins   = aint(rems/60)
	   minsec = mins*60
	   rems   = rems - minsec
	   secs   = rems

	   if ( aveint .eq. 15 )  then

c:	      Time interval == 15, use interp values at secs == 7, 22, 37, 52

	      if ( mod(secs,15) .eq. 7)  go to 300
	      go to 700

	   end if

	   if ( aveint .eq. 10 )  then

c:	      Time interval == 10, use interp values at secs == 5, 15, 25, ...

	      if ( mod(secs,10) .eq. 5)  go to 300
	      go to 700

	   end if

	   if ( aveint .eq.  5 )  then

c:	      Time interval == 5, use interp values at secs == 2, 7, 12, ...

	      if ( mod(secs,5) .eq. 2)  go to 300
	      go to 700

	   end if

c:	   Time interval == 5, use interp values at secs == 0, 1, 2, ...

	   if ( aveint .eq.  1 )  go to 300


	   write (6,261)  aveint
  261	   format (/' Averaging interval ==',i3,' not accounted for by',
	1           ' this program... quitting.'/)

	   call exit


c:	   Compute distance from previous point and cumulative distance

  300	   x(j) = xx(i)
	   y(j) = yy(i)

	   if ( j .eq. 0 )  cumdist = 0

	   if ( j .gt. 0 )  then
	      dx = abs(x(j)-x(j-1))
	      dy = abs(y(j)-y(j-1))
C**	      fct = (-12.057143*(y(j)**2))-(280.577143*y(j))+115890.342857
	      fct = ( dble(-12.057143) * (y(j)**2) )-
	1           ( dble(280.577143) * y(j) ) +
	1           dble(115890.342857)
	      dx = dx * fct
	      dy = dy * dble(111120.0)
	      dist = sqrt((dx**2) + (dy**2))
	      cumdist = cumdist + dist
	   end if

	   if ( hrs .gt. 23)  hrs = hrs-24

	   write (2,321)  hrs,mins,secs, xx(i),yy(i),cumdist
  321	   format (i2.2,':',i2.2,':',i2.2,3x,3f15.6)

	   j = j+1

	   go to 700

  700	   continue

	end do

	dlin1 = dlin2

	go to 200


  900	continue
   
	call exit
	end