Fortran Comparing line in one file to multiple lines in another/FORTRAN

[maria4376]

Hi y'all

I am trying to compare two files, so make one line from one file be compared to alll the lines in the other file until it finds a match where the difference is less than 0.003.

This what I had thought of, but I still think it is just comparing line by line, instead of one line to all the other lines. Any suggestions would be great!

This is what I have so far:


program matchCoords
implicit none

real :: xcoord1, ycoord1,x1,y1,mag1,merr1,sharp1,chi1
real :: xcoord2, ycoord2,x2,y2,mag2,merr2,sharp2,chi2
real, parameter :: arcsec = 0.0003
character (len=50) :: inputfile1, inputfile2, outputfile
integer :: i

!Open input file as unit 15
write(*,*) 'Enter inputfile #1:'
read(*,*) inputfile1
write(*,*) 'Enter inputfile #2'
read(*,*) inputfile2
write(*,*) 'Enter output file name:'
read(*,*) outputfile
open(unit=15, file=inputfile1, status='old')
open(unit=16, file=inputfile2, status='old')
open(unit=17, file=outputfile, status='new')

do i=0,37200
read(16,*) xcoord2, ycoord2,x2,y2,mag2,merr2,sharp2,chi2
do j=0,37000
read(15,*) xcoord1(j), ycoord1(j),x1,y1,mag1,merr1,sharp1,chi1

if(ABS(xcoord1(j)-xcoord2).le.arcsec.and.ABS(ycoord1(i)-ycoor&
&d2).le.arcsec) then

write(17,*) xcoord1(j),ycoord1(j),x1,y1,mag1,merr1,&
&sharp1,chi1,xcoord2,ycoord2,x2,y2,&
&mag2,merr2,sharp2,chi2

 

[gsal]

You have not declared any arrays, yet, you are using indices with xcoord1 and ycoord1.

I don't see the 'end do' lines nor the file rewind...from what I can see, once you go thru the inner loop once (and you get to the end of that file), you will not be able to do that again without a rewind on that file.

I think it is best to simply read the entire array of data, at least, the one that is going to be in the inner loop; in the outer loop, you can get away by just reading one line at a time until the end of file.

So declare arrays for your xxxx1 variables long enough to read the entire file; then, go ahead and do the nested do loop...there will only be need to read a line in the outer loop...in the inner one, you can skip the read statement and go straight to the comparison (using array indices).

 

[maria4376]

Thank you so much, gsal, for taking the timel! I will try that today!