C++ Partial::amplitudeAt方法代码示例

// ---------------------------------------------------------------------------
//	findContribution		(STATIC)
// ---------------------------------------------------------------------------
//	Find and return an iterator range delimiting the portion of pshort that
// 	should be spliced into the distilled Partial plong. If any Breakpoint 
//	falls in a zero-amplitude region of plong, then pshort should contribute,
//	AND its onset should be retained (!!! This is the weird part!!!). 
//  Therefore, if cbeg is not equal to cend, then cbeg is pshort.begin().
//
std::pair< Partial::iterator, Partial::iterator >
findContribution( Partial & pshort, const Partial & plong, 
				  double fadeTime, double gapTime )
{
	//	a Breakpoint can only fit in the gap if there's
	//	enough time to fade out pshort, introduce a
	//	space of length gapTime, and fade in the rest
	//	of plong (don't need to worry about the fade
	//	in, because we are checking that plong is zero
	//	at cbeg.time() + clearance anyway, so the fade 
	//	in must occur after that, and already be part of 
	//	plong):
    //
    //  WRONG if cbeg is before the start of plong.
    //  Changed so that all Partials are faded in and
    //  out before distilling, so now the clearance 
    //  need only be the gap time:
	double clearance = gapTime; // fadeTime + gapTime;
	
	Partial::iterator cbeg = pshort.begin();
	while ( cbeg != pshort.end() && 
			( plong.amplitudeAt( cbeg.time() ) > 0 ||
			  plong.amplitudeAt( cbeg.time() + clearance ) > 0 ) )
	{
		++cbeg;
	}
	
	Partial::iterator cend = cbeg;
	
	// if a gap is found, find the end of the
	// range of Breakpoints that fit in that
	// gap:
	while ( cend != pshort.end() &&
			plong.amplitudeAt( cend.time() ) == 0 &&
			plong.amplitudeAt( cend.time() + clearance ) == 0 )
	{
		++cend;
	}

	// if a gap is found, and it is big enough for at
	// least one Breakpoint, then include the 
	// onset of the Partial:
	if ( cbeg != pshort.end()  )
	{
		cbeg = pshort.begin();
	}
	
	return std::make_pair( cbeg, cend );
}

// ---------------------------------------------------------------------------
//	absorb
// ---------------------------------------------------------------------------
//!	Absorb another Partial's energy as noise (bandwidth), 
//!	by accumulating the other's energy as noise energy
//!	in the portion of this Partial's envelope that overlaps
//!	(in time) with the other Partial's envelope.
//
void 
Partial::absorb( const Partial & other )
{
	Partial::iterator it = findAfter( other.startTime() );
	while ( it != end() && !(it.time() > other.endTime()) )
	{
		//	only non-null (non-zero-amplitude) Breakpoints
		//	abosrb noise energy because null Breakpoints
		//	are used especially to reset the Partial phase,
		//	and are not part of the normal analyasis data:
		if ( it->amplitude() > 0 )
		{
			// absorb energy from other at the time
			// of this Breakpoint:
			double a = other.amplitudeAt( it.time() );
			it->addNoiseEnergy( a * a );
		}	
		++it;
	}
}

//.........这里部分代码省略.........
//!	their Dilator, or Partials having Breakpoints before time 0, both 
//!	of which are probably unusual circumstances.)
//!
//!	\param p is the Partial to dilate.
//	
void
Dilator::dilate( Partial & p ) const
{
	debugger << "dilating Partial having " << p.numBreakpoints() 
			 << " Breakpoints" << endl;

	//	sanity check:
	Assert( _initial.size() == _target.size() );
	
	//	don't dilate if there's no time points, or no Breakpoints:
	if ( 0 == _initial.size() ||
	     0 == p.numBreakpoints() )
	{
		return;
    }
    
	//	create the new Partial:
	Partial newp;
	newp.setLabel( p.label() );
	
	//	timepoint index:
	int idx = 0;
	for ( Partial::const_iterator iter = p.begin(); iter != p.end(); ++iter )
	{
		//	find the first initial time point later 
		//	than the currentTime:
		double currentTime = iter.time();
        idx = std::distance( _initial.begin(), 
                             std::lower_bound( _initial.begin(), _initial.end(), currentTime ) );
        Assert( idx == _initial.size() || currentTime <= _initial[idx] );
        
		//	compute a new time for the Breakpoint at pIter:
		double newtime = 0;
		if ( idx == 0 ) 
		{
			//	all time points in _initial are later than 
			//	the currentTime; stretch if no zero time 
			//	point has been specified, otherwise, shift:
			if ( _initial[idx] != 0. )
				newtime = currentTime * _target[idx] / _initial[idx];
			else
				newtime = _target[idx] + (currentTime - _initial[idx]);
		}
		else if ( idx == _initial.size() ) 
		{
			//	all time points in _initial are earlier than 
			//	the currentTime; shift:
			//
			//	note: size is already known to be > 0, so
			//	idx-1 is safe
			newtime = _target[idx-1] + (currentTime - _initial[idx-1]);
		}
		else 
		{
			//	currentTime is between the time points at idx and
			//	idx-1 in _initial; shift and stretch: 
			//
			//	note: size is already known to be > 0, so
			//	idx-1 is safe
			Assert( _initial[idx-1] < _initial[idx] );	//	currentTime can't wind up 
														//	between two equal times
			
			double stretch = (_target[idx]	- _target[idx-1]) / (_initial[idx] - _initial[idx-1]);			
			newtime = _target[idx-1] + ((currentTime - _initial[idx-1]) * stretch);
		}
		
		//	add a Breakpoint at the computed time:
		newp.insert( newtime, iter.breakpoint() );
	}
	
	//	new Breakpoints need to be added to the Partial at times corresponding
	//	to all target time points that are after the first Breakpoint and
	//	before the last, otherwise, Partials may be briefly out of tune with
	//	each other, since our Breakpoints are non-uniformly distributed in time:
	for ( idx = 0; idx < _initial.size(); ++ idx )
	{
		if ( _initial[idx] <= p.startTime() )
        {
			continue;
        }
		else if ( _initial[idx] >= p.endTime() )
        {
			break;
        }
		else
		{
			newp.insert( _target[idx], 
						 Breakpoint( p.frequencyAt(_initial[idx]), p.amplitudeAt(_initial[idx]),
									 p.bandwidthAt(_initial[idx]), p.phaseAt(_initial[idx]) ) );
		}
	}
	
	//	store the new Partial:
	p = newp;
}