idx       int     // current index in buf
	CAvg      float64 // cumulative average
	prevSMA   float64
	filledBuf bool
}

func newSMA(ln int) *SMA {
	if ln <= 0 {
		ln = defaultWindowSize
	}
	return &SMA{
		buf:    make([]float64, ln),
		window: ln,
		idx:    0,
	}
}

func (s *SMA) addSample(next float64) {
	prev := s.buf[s.idx]
	s.buf[s.idx] = next

	if s.filledBuf {

	)

	vectors := []struct {
		file  string // Optional filename of expected output
		tests []testFnc
	}{{
		// The writer test file was produced with this command:
		// tar (GNU tar) 1.26
		//   ln -s small.txt link.txt
		//   tar -b 1 --format=ustar -c -f writer.tar small.txt small2.txt link.txt
		file: "testdata/writer.tar",
		tests: []testFnc{
			testHeader{Header{
				Typeflag: TypeReg,
				Name:     "small.txt",