OPEN "sunspot.dat" FOR INPUT AS #2
 DIM y(3000)
 PRINT CHR$(12)
 REM GE Copeland
 REM Physics Department
 REM Old Dominion University
 REM Norfolk Va 23504
 REM   4/2001
 REM

 PRINT " FFT of sun spot numbers.... we read the data file"
 PRINT " and process it so WPLOT may plot the data, do an FFT, do the"
 PRINT "plot of data with fit and out put a table of the FFT coefficients."


n = 1994 - 1749
j = 0

REM PRINT n
FOR il = 1 TO n
j = 12 * (il - 1) + 1
REM PRINT "il="; il; "j="; j
INPUT #2, yr, y(j), y(j + 1), y(j + 2), y(j + 3), y(j + 4), y(j + 5), y(j + 6), y(j + 7), y(j + 8), y(j + 9), y(j + 10), y(j + 11)
REM PRINT yr
REM PRINT y(j); y(j + 1); y(j + 2); y(j + 3); y(j + 4); y(j + 5); y(j + 6); y(j + 7); y(j + 8); y(j + 9); y(j + 10); y(j + 11)
NEXT il
CLOSE #2
PRINT "End Year is "; yr
jx = j + 11
PRINT "Final value of month index is "; jx
REM for i = n * 12 - 5 TO jx
REM PRINT i, y(i)
REM NEXT i
PRINT "Entire data set has "; jx; "months."
ymax = -1000
ysum = 0
FOR i = 1 TO jx
ysum = y(i) + ysum
IF y(i) > ymax THEN
ymax = y(i)
ELSE
END IF
NEXT i
yavg = ysum / jx

PRINT "Max value ="; ymax
PRINT "Average value = "; yavg

FOR i = 1 TO 12
ik = 2 ^ i
REM PRINT ik, jx
NEXT i
ikeep = 2048
PRINT " The data truncated to have "; ikeep; " months coverage ="; 2 ^ 11

ymax = -1000
ysum = 0
FOR i = 1 TO ikeep
ysum = y(i) + ysum
IF y(i) > ymax THEN
ymax = y(i)
ELSE
END IF
NEXT i
yavg = ysum / jx

PRINT "Max value ="; ymax
PRINT "Average value = "; yavg


OPEN "PLOT.PLT" FOR OUTPUT AS #2
PRINT #2, "CLRDATA"
PRINT #2, "CLRPLOT"
PRINT #2, "close"
PRINT #2,
PRINT #2, "TITLE The Fast Fourier Transform of Sun Spots Numbers"
PRINT #2, "XLABEL 1749-1920"
PRINT #2, "YLABEL Sunspot Numbers"
PRINT #2, "XSTART 0"
PRINT #2, "XEND "; ikeep
PRINT #2, "XSTEP 1"
PRINT #2, "XTICS 7"
PRINT #2, "XSTEP 0.0825"

PRINT #2, "YSTART 0!"
PRINT #2, "YEND "; ymax
PRINT #2, "YSTEP 0!"
PRINT #2, "READY "; ikeep
REM data goes here
FOR i = 1 TO ikeep
PRINT #2, y(i)
NEXT i
PRINT #2, "SCATTER"
PRINT #2, "PLOT"
PRINT #2, "* MESSAGE Please wait ..."
PRINT #2, "FFT 1"
PRINT #2, "FFTFUNFREQ 200!"
PRINT #2, "XTICS 4"
PRINT #2, "PLOTFFT"
PRINT #2, "* MESSAGE Please wait ..."
PRINT #2, "TITLE Trig fit using 200 FFT ampltitues"
PRINT #2, "* LEGEND0 0.028 0.93 Note:_An_FFT_can_also_be_input_and_inverted."
PRINT #2, "TITLE2 (An FFT can also be input and inverted)"
PRINT #2, "FFTFREQ 200"
PRINT #2, "XTICS 7"
PRINT #2, "PLOT"
PRINT #2, "OUTFFT"
CLOSE #2
END