db.h

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/** @file
 *  @author Bram de Greve (bramz@users.sourceforge.net)
 *  @author Tom De Muer (tomdemuer@users.sourceforge.net)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2007 the Initial Developer.
 *  All Rights Reserved.
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
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 *  deleting the provisions above and replace them with the notice and other 
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 *  a recipient may use your version of this file under either the CPAL or the GPL.
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 *  *** END LICENSE INFORMATION ***
 */

/** @defgroup dB
 *  @brief collection of conversion functions for dB
 */

#ifndef LASS_GUARDIAN_OF_INCLUSION_NUM_DB_H
#define LASS_GUARDIAN_OF_INCLUSION_NUM_DB_H

#include "num_common.h"
#include "num_traits.h"

#define LASS_NUM_DB_10_OVER_LN10 4.3429448190325182765112891891661
#define LASS_NUM_DB_20_OVER_LN10 8.6858896380650365530225783783321
#define LASS_NUM_DB_LN10_OVER_10 0.23025850929940456840179914546844
#define LASS_NUM_DB_LN10_OVER_20 0.11512925464970228420089957273422

namespace lass
{
    namespace num
    {
        /** power to decibels: y = 10 * log10(x)
         *  @ingroup dB
         */
        template <typename T> inline T pow2dB(const T& power)
        {
            return T(LASS_NUM_DB_10_OVER_LN10) * num::log(power);
        }

        /** amplitude to decibels: y = 20 * log10(x)
         *  @ingroup dB
         */
        template <typename T> inline T amp2dB(const T& amplitude)
        {
            return T(LASS_NUM_DB_20_OVER_LN10) * num::log(amplitude);
        }

        /** decibels to power: y = num::pow(10, x / 10)
         *  @ingroup dB
         */
        template <typename T> inline T dB2pow(const T& decibels)
        {
            return num::exp(T(LASS_NUM_DB_LN10_OVER_10) * decibels);
        }

        /** decibels to amplitude: y = num::pow(10, x / 20)
         *  @ingroup dB
         */
        template <typename T> inline T dB2amp(const T& decibels)
        {
            return num::exp(T(LASS_NUM_DB_LN10_OVER_20) * decibels);
        }

        /** Converts an absolute acoustical pressure into decibels.
         *  @ingroup dB
         */
        template< typename T >  T   p2dB( const T& iValue );

        /** Converts a absolute acoustical power into decibels.
         *  @ingroup dB
         */
        template< typename T >  T   W2dB( const T& iValue );

        /** Converts an intensity into decibels.
         *  @ingroup dB.
         *  The intensity represents the intensity in all directions expressed in Watts/m^2,
         *  referenced to 10^-12.
         */
        template< typename T >  T   I2dB( const T& iValue );

        /** Converts decibels into a pressure .
         *  @ingroup dB
         */
        template< typename T >  T   dB2p( const T& iValue );

        /** Converts decibels into a power.
         *  @ingroup dB
         */
        template< typename T >  T   dB2W( const T& iValue );

        /** Converts decibels into an intensity.
         *  @ingroup dB
         *  The intensity represents the intensity in all directions expressed in Watts/m^2,
         *  referenced to 10^-12
         */
        template< typename T >  T   dB2I( const T& iValue );
    }
}

#include "db.inl"

#endif