Fixed bug in peak interpolation algorithm in xtract_peak_spectrum()

2 files changed, 3 insertions, 0 deletions

diff --git a/xtract/xtract_delta.h b/xtract/xtract_delta.h
index 6e19708..152a891 100644
--- a/xtract/xtract_delta.h
+++ b/xtract/xtract_delta.h
@@ -39,6 +39,7 @@ extern "C" {
 
 /** \brief Extract flux 
  *
+ *  \note FIX: don't be lazy -- take the lnorm of the difference vector! 
  * An alias for xtract_lnorm()
  */
 int xtract_flux(const float *data, const int N, const void *argv , float *result);
diff --git a/xtract/xtract_scalar.h b/xtract/xtract_scalar.h
index 9bccb01..fdfb42a 100644
--- a/xtract/xtract_scalar.h
+++ b/xtract/xtract_scalar.h
@@ -394,6 +394,8 @@ int xtract_hps(const float *data, const int N, const void *argv, float *result);
  * \param *result: the pitch of N values from the array pointed to by *data
  *
  * This algorithm is based on the AMDF, with peak and centre clipping. It would benefit from further improvements to improve noise robustness and overall efficiency
+ *
+ * It is based on suggestion by Robert Bristow-Johnson in a discussion on the comp.dsp mailing list, subject "Reference implementation of pitch detection"
  * 
  */
 int xtract_f0(const float *data, const int N, const void *argv, float *result);