[Kst] extragear/graphics/kst/src/libkstmath

[Duncan Hanson]

SVN commit 554016 by dhanson:

CCBUG:129598 i find that the psds calculated with psdcalculator differ from those calculated by KstPSD because of normalization. i've reverted PSDCalculator to the original normalization- but I can't see that I've done anything wrong.

 M  +12 -2     psdcalculator.cpp  


--- trunk/extragear/graphics/kst/src/libkstmath/psdcalculator.cpp #554015:554016
@@ -33,7 +33,7 @@
 #define PSDMINLEN 2
 #define PSDMAXLEN 27
 
-double PSDCalculator::cabs2(double r, double i) {
+inline double PSDCalculator::cabs2(double r, double i) {
   return r*r + i*i;
 }
 
@@ -184,7 +184,7 @@
     updateWindowFxn(apodizeFxn, gaussianSigma);
   }
 
-  int currentCopyLen;
+  int currentCopyLen, nsamples = 0;
   int i_samp, i_subset, ioffset;
 
   memset(output, 0, sizeof(double)*outputLen); // initialize output.
@@ -246,6 +246,8 @@
       }
     }
 
+    nsamples += currentCopyLen;
+
     rdft(_awLen, 1, _a); //real discrete fourier transorm on _a.
 
     output[0] += _a[0] * _a[0];
@@ -255,6 +257,9 @@
     }
   }
 
+  // FIXME: NORMALIZATION. 
+  /* This normalization doesn't give the same results as the original KstPSD.
+
   double frequencyStep = .5*(double)inputSamplingFreq/(double)(outputLen-1);
 
   //normalization factors which were left out earlier for speed. 
@@ -262,7 +267,12 @@
   //    - /(_awLen*_awLen) for the constant Wss from numerical recipes in C. (ensure that the window function agrees with this.)
   //    - /i_subset to average the powers in all the subsets.
   double norm = 2.0/(double)_awLen/(double)_awLen/(double)i_subset;
+  */
 
+  // original normalization
+  double frequencyStep = 2.0*(double)inputSamplingFreq/(double)nsamples; //OLD value for frequencyStep.
+  double norm = 2.0/(double)nsamples*2.0/(double)nsamples; //OLD value for norm.
+
   switch (outputType) {
   default:
     case PSDAmplitudeSpectralDensity: // amplitude spectral density (default) [V/Hz^1/2]