!------------------------------------------------------------------------------
! DETREND.PRG
!------------------------------------------------------------------------------
!       purpose: fit a Fourier series of sine/cosines to the data and subtract 
!                them then
!        author: B. Gaensicke
! last revision: 2010-04-30 
!
! allow for the number of harmonics to be specified
! dump MIDAS log to detrend.log to fetch the STDOUT output from sinefit/tsa
!------------------------------------------------------------------------------
! You need to specify 
!
! p1 = input file
! p2 = output file
! p3 = best guess of the frequency
! p4 = number of iterations in the fit [1: do not fit the frequency]
! p5 = number of harmonics to be used [0=constant, 1=fundamental, 2=fund.+harm.]
!------------------------------------------------------------------------------

set/context tsa

define/par p1 tsa             c "Input  file       = "
define/par p2 tsa_resid       c "Output file       = "
define/par p3 0               n "f[d-1]            = "
define/par p4 30              n "No. of iterations = "
define/par p5 1               n "No. of harmonics  = "

define/local ifile/c/1/80 {p1}
define/local ofile/c/1/80 {p2}
define/local freq/d/1/1   {p3}
define/local nit/i/1/1    {p4}
define/local nharm/i/1/1/ {p5}

define/local start/d/1/1  0
define/local end/d/1/1    0

start = freq*0.9
end   = freq*1.1

define/local step/d/1/1   0.
define/local nstep/i/1/1  5000
step = (end-start)/nstep

! Read in data
create/table target * * {ifile} $MID_WORK/period.fmt

set/tsa starttsa = {start}
set/tsa steptsa  = {step}
set/tsa nsteps   = {nstep}

! fit and subtract sine waves

write/out sinefit/tsa target resid {freq} {nharm} {nit}
sinefit/tsa target resid {freq} {nharm} {nit}

assign/print file detrend.log
print/log

assign/print file tmp.dat
print/table resid :time :value N
$ awk '{print $2,$3}' tmp.dat > {ofile}

return