Substituting minus infinity with numeric_limits infinity() for float and double

include/ITAConstants.h

@@ -51,15 +51,6 @@ namespace ITAConstants
 	// Epsilon (distance quantization)
 	static float EPS_F_L = 1.0e-5f; // 10 micro meter
 	static double EPS_D_L = 1.0e-5f; // 10 micro meter
-
-	// Symbolische Konstante für den Verstärkungsfaktor -oo dB
-	/* TODO: Dies ist hardgecodet eine verdammt große Double-Zahl.
-			 Laut Internet ist die größte negative Zahl -1.79769313486231570 x 10^308.
-			 Am besten wäre hier eine symbolische Minus-Unendlich.
-			 Da muss noch geprüft werden, ob sich so etwas mit double
-			 realisieren lässt [fwe]. */
-	const double DECIBEL_MINUS_INFINITY = -1.5E-308;
-
 };
 
 #endif // INCLUDE_WATCHER_ITA_CONSTANTS

src/ITANumericUtils.cpp

@@ -3,6 +3,8 @@
 #include <ITAConstants.h>
 #include <ITAException.h>
 
+#include <numeric>
+
 using namespace ITAConstants;
 
 int getExp2(unsigned int x) {
@@ -117,26 +119,34 @@ float correctAngle360(float phi) {
 	return fmodf(phi, 360.0f);
 }
 
-double db10_to_ratio(double db) {
-	return (db == DECIBEL_MINUS_INFINITY ? 0 : pow(10, db/10.0));
+double db10_to_ratio( const double db )
+{
+	return ( db == -std::numeric_limits< double >::infinity() ? 0.0f : pow( 10.0f, db / 10.0f ) );
 }
 
-double ratio_to_db10(double r) {
-	if (r < 0) ITA_EXCEPT0(INVALID_PARAMETER);
-	return (r == 0 ? DECIBEL_MINUS_INFINITY : 10*log10(r));
+double db20_to_ratio( const double db )
+{
+	return ( db == -std::numeric_limits< double >::infinity() ? 0.0f : pow( 10.0f, db / 20.0f ) );
 }
 
-double db20_to_ratio(double db) {
-	return (db == DECIBEL_MINUS_INFINITY ? 0 : pow(10, db/20.0));
+double ratio_to_db10( const double r )
+{
+	if( r < 0.0f )
+		ITA_EXCEPT1( INVALID_PARAMETER, "Conversion to decibel not possible for negative values" );
+
+	if( r == 0.0f )
+		return -std::numeric_limits< double >::infinity();
+	else
+		return 10.0f * log10( r );
 }
 
-double ratio_to_db20( double r )
+double ratio_to_db20( const double r )
 {
 	if( r < 0.0f )
 		ITA_EXCEPT1( INVALID_PARAMETER, "Conversion to decibel not possible for negative values" );
 
 	if( r == 0.0f )
-		return DECIBEL_MINUS_INFINITY;
+		return -std::numeric_limits< double >::infinity();
 	else
 		return 20.0f * log10( r );
 }

tests/ITABaseSpectrumTests.cpp

@@ -50,10 +50,20 @@ void test_ratio_to_db()
 	CITAThirdOctaveMagnitudeSpectrum oTOSpectrumConvertToRatio;
 	oTOSpectrumConvertToRatio.SetName( "Test unit gain spectrum to db" );
 	oTOSpectrumConvertToRatio.SetValueUnit( "(gain)" );
-	oTOSpectrumConvertToRatio.SetZero();
+	oTOSpectrumConvertToRatio.SetIdentity(); // db -> all zeros
+
+	for( int n = 0; n < oTOSpectrumConvertToRatio.GetNumBands(); n++ )
+		oTOSpectrumConvertToRatio[ n ] = ratio_to_db10( oTOSpectrumConvertToRatio[ n ] ); // zero to db -> -inf
+
+	oTOSpectrumConvertToRatio.SetValueUnit( "dB" );
+
+	cout << oTOSpectrumConvertToRatio << endl;
 
+	// Convert gains "1"
+	oTOSpectrumConvertToRatio.SetIdentity(); // db -> all zeros
+	oTOSpectrumConvertToRatio.Add( 1.0f ); // gains now all 1.0
 	for( int n = 0; n < oTOSpectrumConvertToRatio.GetNumBands(); n++ )
-		oTOSpectrumConvertToRatio[ n ] = ratio_to_db10( oTOSpectrumConvertToRatio[ n ] );
+		oTOSpectrumConvertToRatio[ n ] = ratio_to_db10( oTOSpectrumConvertToRatio[ n ] ); // ratio 1 to db -> 0
 
 	oTOSpectrumConvertToRatio.SetValueUnit( "dB" );