modified the chebyshev12 routine to put out readily normalized circular harmonics and added

[mtx_circular_harmonics] to the file mtx_spherical_harmonics, as well as a corresponding helpfile.
why: useful for circular (1D) ambisonics, e.g. ...


svn path=/trunk/externals/iem/iemmatrix/; revision=11792

1 files changed, 9 insertions, 0 deletions

diff --git a/src/mtx_spherical_harmonics/sharmonics_normalization.c b/src/mtx_spherical_harmonics/sharmonics_normalization.c
index ca97292..d7fe00a 100644
--- a/src/mtx_spherical_harmonics/sharmonics_normalization.c
+++ b/src/mtx_spherical_harmonics/sharmonics_normalization.c
@@ -27,8 +27,14 @@ SHNorml *sharmonics_normalization_new (const size_t nmax) {
          wn=0;
       }
       else {
+	 /*
+         deprecated:
          // computing N_n^m for m=0, wrongly normalized
          wn->n[0]=sqrt(1/(2*M_PI));
+	 */
+
+         // computing N_n^m for m=0,
+         wn->n[0]=oneoversqrt2;
          for (n=1,n0=1; n<=nmax; n++) {
             wn->n[n0]=wn->n[0] * sqrt(2*n+1);
             n0+=n+1;
@@ -40,11 +46,14 @@ SHNorml *sharmonics_normalization_new (const size_t nmax) {
             }
             n0+=n+1;
          }
+	 /*
+	 deprecated:
          // correcting normalization of N_n^0
          for (n=0,n0=0; n<=nmax; n++) {
             wn->n[n0]*=oneoversqrt2;
             n0+=n+1;
          }
+	 */
       }
    }
    return wn;