src/cvec.h: add formula

diff --git a/src/cvec.h b/src/cvec.h
index be4bbab..7c826b6 100644 (file)
--- a/src/cvec.h
+++ b/src/cvec.h
@@ -235,6 +235,8 @@ void cvec_zeros(cvec_t *s);
   \param s input cvec to compress
   \param lambda value to use for normalisation
 
+  \f$ S_k = log( \lambda * S_k + 1 ) \f$
+
 */
 void cvec_logmag(cvec_t *s, smpl_t lambda);