dayofyear.gsf

function dayofyear( time )
  length = math_strlen( time )
  year   = substr( time, length-3, 4 )
  cmonth = substr( time, length-6, 3 )
  cmonth = chcase( cmonth, 'upper' )
  day = substr( time, length-8, 2 )

  if( cmonth = 'JAN' ) ; month = 1  ; endif
  if( cmonth = 'FEB' ) ; month = 2  ; endif
  if( cmonth = 'MAR' ) ; month = 3  ; endif
  if( cmonth = 'APR' ) ; month = 4  ; endif
  if( cmonth = 'MAY' ) ; month = 5  ; endif
  if( cmonth = 'JUN' ) ; month = 6  ; endif
  if( cmonth = 'JUL' ) ; month = 7  ; endif
  if( cmonth = 'AUG' ) ; month = 8  ; endif
  if( cmonth = 'SEP' ) ; month = 9  ; endif
  if( cmonth = 'OCT' ) ; month = 10 ; endif
  if( cmonth = 'NOV' ) ; month = 11 ; endif
  if( cmonth = 'DEC' ) ; month = 12 ; endif

  doy = 0
  m = 1
  while( m < month )
    doy = doy + days( year, m )
    m = m + 1
  endwhile
  doy = doy + day
return doy