Fixed bug in peak interpolation algorithm in xtract_peak_spectrum()

3 files changed, 4 insertions, 1 deletions

diff --git a/src/delta.c b/src/delta.c
index 25d380b..b1effd0 100644
--- a/src/delta.c
+++ b/src/delta.c
@@ -26,6 +26,7 @@
 
 int xtract_flux(const float *data, const int N, const void *argv , float *result){
 
+    /* FIX: don't be lazy -- take the lnorm of the difference vector! */
     return xtract_lnorm(data, N, argv, result);
 
 }
diff --git a/src/scalar.c b/src/scalar.c
index 4a2b672..d2bc317 100644
--- a/src/scalar.c
+++ b/src/scalar.c
@@ -434,6 +434,8 @@ int xtract_spread(const float *data, const int N, const void *argv, float *resul
 	den += data[n];
     }
 
+    /* FIX: spectral spread is mathematically equivalent to spectral variance --
+     * here we are computing the spectral standard deviation */
     *result = sqrtf(num / den);
 
     return XTRACT_SUCCESS;
diff --git a/src/vector.c b/src/vector.c
index 449cd0d..b891111 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -436,7 +436,7 @@ int xtract_peak_spectrum(const float *data, const int N, const void *argv, float
     for(n = 1; n < N; n++){
         if(input[n] >= threshold){
             if(input[n] > input[n - 1] && input[n] > input[n + 1]){
-                result[N + n] = q * (n + (p = .5 * (y = input[n-1] - 
+                result[N + n] = q * (n + (p = .5 * ((y = input[n-1]) - 
 				(y3 = input[n+1])) / (input[n - 1] - 2 * 
 				    (y2 = input[n]) + input[n + 1])));
                 result[n] = y2 - .25 * (y - y3) * p;