Changeset 9499eefb for src/mathutils.h

Timestamp:

Apr 8, 2013, 5:19:10 PM (11 years ago)

Author:

Paul Brossier <piem@piem.org>

Branches:

feature/autosink, feature/cnn, feature/cnn_org, feature/constantq, feature/crepe, feature/crepe_org, feature/pitchshift, feature/pydocstrings, feature/timestretch, fix/ffmpeg5, master, pitchshift, sampler, timestretch, yinfft+

Children:

69d642a

Parents:

002563f

Message:

src/mathutils.{c,h}: add fvec_quadratic_peak_pos, a fixed replacement for fvec_quadint

File:

• src/mathutils.h (modified) (1 diff)

src/mathutils.h

@@ -236 +236 @@
 smpl_t fvec_quadint (fvec_t * x, uint_t pos);
 
+/** finds exact peak index by quadratic interpolation
+
+  See [Quadratic Interpolation of Spectral
+  Peaks](https://ccrma.stanford.edu/~jos/sasp/Quadratic_Peak_Interpolation.html),
+  by Julius O. Smith III
+
+  \f$ p_{frac} = \frac{1}{2} \frac {x[p-1] - x[p+1]} {x[p-1] - 2 x[p] + x[p+1]} \in [ -.5, .5] \f$
+
+  \param x vector to get the interpolated peak position from
+  \param p index of the peak in vector `x`
+  \return \f$ p + p_{frac} \f$ exact peak position of interpolated maximum or minimum
+
+*/
+smpl_t fvec_quadratic_peak_pos (fvec_t * x, uint_t p);
+
 /** Quadratic interpolation using Lagrange polynomial.