{WRITTEN BY MUTLU DOGRUEL}

{AUTOCORRELATION TO EL NINO DATA USING DIRECT METHOD}

program elnino;

uses crt;

const n=168;

var

sum:real;

el:array [1..n] of real;

acov:array [0..n-1] of real;

txt1,txt2:text;

i,j:integer;

BEGIN

clrscr;

{THE DATA IS OBTAINED FROM “ELNINO.DAT”}

assign(txt1,'elnino.dat');

reset(txt1);

i:=0;sum:=0.0;

while not(eof(txt1)) do

begin

readln(txt1,el[i]);

sum:=sum+el[i];

i:=i+1;

end;

for i:=0 to n-1 do

begin

el[i]:=el[i]-sum/n;

el[i+n]:=0.0;

end;

for j:=0 to n-1 do

begin

acov[j]:=0.0;

for i:=1 to n-1-j do

acov[j]:=acov[j]+el[i]*el[i+j];

end;

assign(txt2,'correct.txt');

rewrite(txt2);

for i:=0 to n-1 do

writeln(txt2,i,' ', acov[i]/acov[0]);

close(txt1);

close(txt2);

readln;

END.

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DATA BETWEEN 1962-1975 FOR EL NINO:

12.9

11.3

10.6

11.2

10.9

7.5

7.7

11.7

12.9

14.3

10.9

13.7

17.1

14.0

15.3

8.5

5.7

5.5

7.6

8.6

7.3

7.6

12.7

11.0

12.7

12.9

13.0

10.9

10.4

10.2

8.0

10.9

13.6

10.5

9.2

12.4

12.7

13.3

10.1

7.8

4.8

3.0

2.5

6.3

9.7

11.6

8.6

12.4

10.5

13.3

10.4

8.1

3.7

10.7

5.1

10.4

10.9

11.7

11.4

13.7

14.1

14.0

12.5

6.3

9.6

11.7

5.0

10.8

12.7

10.8

11.8

12.6

15.7

12.6

14.8

7.8

7.1

11.2

8.1

6.4

5.2

12.0

10.2

12.7

10.2

14.7

12.2

7.1

5.7

6.7

3.9

8.5

8.3

10.8

16.7

12.6

12.5

12.5

9.8

7.2

4.1

10.6

10.1

10.1

11.9

13.6

16.3

17.6

15.5

16.0

15.2

11.2

14.3

14.5

8.5

12.0

12.7

11.3

14.5

15.1

10.4

11.5

13.4

7.5

0.6

0.3

5.5

5.0

4.6

8.2

9.9

9.2

12.5

10.9

9.9

8.9

7.6

9.5

8.4

10.7

13.6

13.7

13.7

16.5

16.8

17.1

15.4

9.5

6.1

10.1

9.3

5.3

11.2

16.6

15.6

12.0

11.5

8.6

13.8

8.7

8.6

8.6

8.7

12.8

13.2

14.0

13.4

14.8

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