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Gyoto::Astrobj::Standard Class Reference

Astronomical objects defined bya a potential/distance. More...

#include <GyotoStandardAstrobj.h>

Inheritance diagram for Gyoto::Astrobj::Standard:
Gyoto::Astrobj::Generic Gyoto::Functor::Double_constDoubleArray Gyoto::SmartPointee Gyoto::Astrobj::Torus Gyoto::Astrobj::UniformSphere Gyoto::Astrobj::FixedStar Gyoto::Astrobj::Star

Public Member Functions

 Standard ()
 Default constructor.
 Standard (double radmax)
 Set rmax in constructor.
 Standard (std::string kind)
 Set kind in constructor.
 Standard (const Standard &)
 Copy constructor.
virtual ~Standard ()
 Destructor: does nothing.
virtual void setSafetyValue (double val)
virtual double getSafetyValue () const
virtual int Impact (Gyoto::Photon *ph, size_t index, Astrobj::Properties *data=NULL)
 does a photon at these coordinates impact the object?
virtual double operator() (double const coord[4])=0
virtual void getVelocity (double const pos[4], double vel[4])=0
virtual double giveDelta (double coord[8])
virtual int setParameter (std::string name, std::string content)
 Called from setParameters()
virtual void fillElement (FactoryMessenger *fmp) const
 called from Factory
virtual Genericclone () const =0
 "Virtual" copy constructor
virtual SmartPointer
< Metric::Generic
getMetric () const
virtual void setMetric (SmartPointer< Metric::Generic >)
virtual double getRmax ()
 Get maximal distance from center of coordinate system.
const std::string getKind () const
 Get the kind of the Astrobj (e.g. "Star")
virtual void setRmax (double val)
 Set maximal distance from center of coordinate system.
virtual void unsetRmax ()
 Set rmax_set_ to 0.
void setFlag_radtransf (int flag)
 Set whether the object is optically thin.
int getFlag_radtransf () const
 Query whether object is optically thin.
virtual Quantity_t getDefaultQuantities ()
virtual void setParameters (FactoryMessenger *fmp)
 Main loop in Subcontractor_t function.
virtual void processHitQuantities (Photon *ph, double *coord_ph_hit, double *coord_obj_hit, double dt, Astrobj::Properties *data) const
virtual double emission (double nu_em, double dsem, double coord_ph[8], double coord_obj[8]=NULL) const
 INVARIANT emission j_{}/^{2}.
virtual double integrateEmission (double nu1, double nu2, double dsem, double c_ph[8], double c_obj[8]=NULL) const
 ^nu2 I_nu dnu (or j_nu)
virtual double transmission (double nuem, double dsem, double coord[8]) const
 Transmission: exp( {} * dsem )
void checkPhiTheta (double coord[8]) const
virtual double operator() (double const data[])=0

Protected Types

typedef Gyoto::SmartPointer
< Gyoto::SmartPointee
Subcontractor_t (Gyoto::FactoryMessenger *)
 A subcontractor builds an object upon order from the Factory.

Protected Member Functions

void incRefCount ()
 Increment the reference counter. Warning: Don't mess with the counter.
int decRefCount ()
 Decrement the reference counter and return current value. Warning: Don't mess with the counter.
int getRefCount ()
 Get the current number of references.

Protected Attributes

double critical_value_
 see operator()(double const coord[4]) const
double safety_value_
 see operator()(double const coord[4]) const
SmartPointer
< Gyoto::Metric::Generic
gg_
double rmax_
 Maximum distance to the center of the coordinate system.
int rmax_set_
 Never recompute rmax: it was externally set.
const std::string kind_
 Kind of object (e.g. "Star"...)
int flag_radtransf_
 1 if radiative transfer inside Astrobj, else 0

Friends

class Gyoto::SmartPointer< Gyoto::Astrobj::Standard >

Detailed Description

Astronomical objects defined bya a potential/distance.

Many geometrically thick objects can be defined by the value of a function of the 4 coordinates, and their emission can often be defined in terms of an emission law and of a transmission law.

This is a base class for this standard case which simplifies a lot writting new Astrobjs.

It is either to implement a sub-class of Astrobj::Standard than a sub-class of Astrobj::Generic. In particular, there is no need to implement the Generic::Impact() function. Instead, one needs to implement a few much simpler functions and most of the complex ray-tracing algorithms and heuristics is implemented in Standard::Impact(). It is recommended to read first the introduction in the Gyoto::Astrobj namespace documentation.

The geometrical shape of a Gyoto::Astrobj::Standard object is yielded by a function of the 4 position vector. This function is implemented as operator()(). The velocity field of the fluid is implemented in the getVelocity() method. The emission(), integrateEmission() and transmission() methods implement the radiative transfer primitives for this object. Finally, you may choose to reimplement processHitQuantities() and Impact(), but this should not be necessary (that is the all point of the Standard class).

Like any other Astrobj::Generic sub-classes, an Astrobj::Standard subclass should register an Astrobj::Subcontractor_t function using the Astrobj::Register() function. See also Writing plug-ins for Gyoto .

Member Typedef Documentation

typedef Gyoto::SmartPointer<Gyoto::SmartPointee> Gyoto::SmartPointee::Subcontractor_t(Gyoto::FactoryMessenger *)
inherited

A subcontractor builds an object upon order from the Factory.

Various classes need to provide a subcontractor to be able to instanciate themselves upon order from the Factory. A subcontractor is a function (often a static member function) which accepts a pointer to a FactoryMessenger as unique parameter, communicates with the Factory using this messenger to read an XML description of the object to build, and returns this objet. SmartPointee::Subcontractor_t* is just generic enough a typedef to cast to and from other subcontractor types: Astrobj::Subcontractor_t, Metric::Subcontractor_t, Spectrum::Subcontractor_t. A subcontractor needs to be registered using the relevant Register() function: Astrobj::Register(), Metric::Register(), Spectrum::Register().

Constructor & Destructor Documentation

Gyoto::Astrobj::Standard::Standard ( )

Default constructor.

kind_ = "Default", rmax_ = 0., rmax_set_ = 0.

Gyoto::Astrobj::Standard::Standard ( double  radmax)

Set rmax in constructor.

kind_ = "Default", rmax_ = radmax, rmax_set_ = 1.

Gyoto::Astrobj::Standard::Standard ( std::string  kind)

Set kind in constructor.

kind_ = kind, rmax_ = 0., rmax_set_ = 0.

Gyoto::Astrobj::Standard::Standard ( const Standard )

Copy constructor.

Make a deep copy of an Astrobj::Standard instance

Member Function Documentation

void Gyoto::Astrobj::Generic::checkPhiTheta ( double  coord[8]) const
inherited

checkPhiTheta() Modifies coord if the corrdinates are spherical-like so that coord[2]=theta is in [0,pi] and coord[3]=phi is in [0,2pi]. Important to use in all astrobj in spherical coordinates to prevent "z-axis problems".

virtual Generic* Gyoto::Astrobj::Generic::clone ( ) const
pure virtualinherited

"Virtual" copy constructor

 This method must be implemented by the various Astrobj::Generic
 subclasses in order to support cloning:
SmartPointer<Astrobj> deep_copy = original->clone();
 Implementing it is very straightforward, as long as the copy
 constructor Generic(const Generic& ) has been implemented:
MyAstrobj* MyAstrobj::clone() const { return new MyAstrobj(*this); }

Implemented in Gyoto::Astrobj::Star, Gyoto::Astrobj::PatternDisk, Gyoto::Astrobj::Disk3D, Gyoto::Astrobj::ThinDisk, Gyoto::Astrobj::DynamicalDisk, Gyoto::Astrobj::Complex, Gyoto::Astrobj::Disk3D_BB, Gyoto::Astrobj::Torus, Gyoto::Astrobj::PageThorneDisk, Gyoto::Astrobj::ThinDiskPL, Gyoto::Astrobj::PatternDiskBB, and Gyoto::Astrobj::FixedStar.

virtual double Gyoto::Astrobj::Generic::emission ( double  nu_em,
double  dsem,
double  coord_ph[8],
double  coord_obj[8] = NULL 
) const
virtualinherited

INVARIANT emission j_{}/^{2}.

Called by the default implementation for processHitQuantities().

emission() computes the intensity I_nu emitted by the small volume of length dsem. It should take self-absorption along dsem into account.

Reminder :

  • intensity = I_nu [erg cm^-2 s^-1 ster^-1 Hz^-1];
  • invariant intensity = I_nu/nu^3, which has the same value in any frame;
  • emission coefficient = j_nu [erg cm^-3 s^-1 ster^-1 Hz^-1] , defined by dI_nu = j_nu*ds, where ds is the distance travelled by the photon inside the object;
  • invariant emission coef = j_nu/nu^2, which has the same value in any frame.

The equation used for radiative transfer (without absorption) is: d(I_nu/nu^3)/dlambda = (j_nu/nu^2) [*] where lambda is the integration parameter along the null geodesic.

NB: Let us consider a particular observer, 
    with nu being the frequency measured by this observer,
    and ds being the proper distance (as measured by the observer) 
    that the photon travels as it moves
    from lambda to lambda+dlambda along its geodesic.
    Then it can be shown that :
                    dlambda = ds/nu
    This shows that Eq. [*] is homogeneous.

The default implementation returns 1. if optically thick and dsem if optically thin. It allows for a quick implementation of your object for visualization purposes.

Parameters
nu_emFrequency at emission
dsemlength over which to integrate inside the object
coord_phPhoton coordinate
coord_objEmitter coordinate at current photon position

Reimplemented in Gyoto::Astrobj::PatternDisk, Gyoto::Astrobj::UniformSphere, Gyoto::Astrobj::Torus, Gyoto::Astrobj::DynamicalDisk, Gyoto::Astrobj::Disk3D_BB, Gyoto::Astrobj::PageThorneDisk, Gyoto::Astrobj::PatternDiskBB, and Gyoto::Astrobj::ThinDiskPL.

virtual void Gyoto::Astrobj::Standard::fillElement ( FactoryMessenger fmp) const
virtual

called from Factory

Astrobj implementations should impement fillElement to save their parameters to XML and call the generic implementation to save generic parts such as Flag_radtrans: Generic::fillElement(fmp).

Reimplemented from Gyoto::Astrobj::Generic.

Reimplemented in Gyoto::Astrobj::Star, Gyoto::Astrobj::UniformSphere, Gyoto::Astrobj::Torus, and Gyoto::Astrobj::FixedStar.

virtual Quantity_t Gyoto::Astrobj::Generic::getDefaultQuantities ( )
virtualinherited

Return a Gyoto::Quantity_t suitable as input to Gyoto::Scenery::setRequestedQuantities() to set de default quantities to compute for this object. The default of these defaults GYOTO_QUANTITY_INTENSITY.

int Gyoto::Astrobj::Generic::getFlag_radtransf ( ) const
inherited

Query whether object is optically thin.

See setFlag_radtransf(int flag).

virtual SmartPointer<Metric::Generic> Gyoto::Astrobj::Generic::getMetric ( ) const
virtualinherited

Get the Metric

Reimplemented in Gyoto::Astrobj::Star.

virtual double Gyoto::Astrobj::Generic::getRmax ( )
virtualinherited

Get maximal distance from center of coordinate system.

Get maximal distance from center of coordinate system at which a Photon may hit the object.

Child classes may use the rmax_ member to cache this value.

It can also be set using setRmax(). If setRmax has been used to set rmax_, getRmax() must not recompute it.

Reimplemented in Gyoto::Astrobj::Star, and Gyoto::Astrobj::Torus.

virtual void Gyoto::Astrobj::Standard::getVelocity ( double const  pos[4],
double  vel[4] 
)
pure virtual

Used by Standard::Impact().

Fill vel with the 4-vector velocity of the fluid at 4-position pos.

Parameters
posinput, 4-position at which to compute velocity;
veloutput, 4-velocity at pos.

Implemented in Gyoto::Astrobj::UniformSphere, Gyoto::Astrobj::Star, Gyoto::Astrobj::Torus, and Gyoto::Astrobj::FixedStar.

virtual double Gyoto::Astrobj::Standard::giveDelta ( double  coord[8])
virtual

Used by Standard::Impact().

Gives the requested integration step delta_t (in coordinate time t) between two neighbooring points along a portion of geodesic inside an astrobj

Parameters
coordinput coordinate at which delta_t is given
virtual int Gyoto::Astrobj::Standard::Impact ( Gyoto::Photon ph,
size_t  index,
Astrobj::Properties data = NULL 
)
virtual

does a photon at these coordinates impact the object?

Impact() checks whether a Photon impacts the object between two integration steps of the photon's trajectory (those two steps are photon->getCoord(index, coord1) and photon->getCoord(index+1, coord2)). Impact returns 1 if the photon impacts the object between these two steps, else 0. In many cases of geometrically thick obects, the implementation Astrobj::Standard::Impact() will be fine.

Impact will call Generic::processHitQuantities() (which is virtual and may be re-implemented) to compute observable properties on demand: if the data pointer is non-NULL, the object will look in it for pointers to properties which apply to its kind. If a pointer to a property known to this object is present, then the property is computed and store at the pointed-to adress. For instance, all objects know the "intensity" property. If data->intensity != NULL, the instensity is computed and stored in *data->intensity.

If data is non-NULL and only in this case, processHitQuantities() will also call ph->transmit() to update the transmissions of the Photon (see Photon::transmit(size_t, double)). This must not be done if data is NULL (see Astrobj::Complex::Impact() for an explanation).

Parameters
phGyoto::Photon aimed at the object;
indexIndex of the last photon step;
dataPointer to a structure to hold the observables at impact.
Returns
1 if impact, 0 if not.

Implements Gyoto::Astrobj::Generic.

virtual double Gyoto::Astrobj::Generic::integrateEmission ( double  nu1,
double  nu2,
double  dsem,
double  c_ph[8],
double  c_obj[8] = NULL 
) const
virtualinherited

^nu2 I_nu dnu (or j_nu)

Compute the integral of emission() from nu1 to nu2. The default implementation is a numerical integrator which works well enough and is reasonably fast if emission() is a smooth function (i.e. no emission or absorption lines). If possible, it is wise to implement an analytical solution. It is used by processHitQuantities to compute the "BinSpectrum" quantity which is the most physical: it is the only quantity that can be actually measured directly by a real-life instrument.

Reimplemented in Gyoto::Astrobj::UniformSphere, and Gyoto::Astrobj::Torus.

virtual double Gyoto::Astrobj::Standard::operator() ( double const  coord[4])
pure virtual

A potential, distance, or whatever function such that operator()(double coord[4]) < critical_value_ if and only if coord is inside the object. This function is used by the default implmenetation of Impact(). If Impact() is overloaded, it is not necessary to overload operator()(double coord[4]). The default implementation throws an error.

Implemented in Gyoto::Astrobj::UniformSphere, and Gyoto::Astrobj::Torus.

virtual void Gyoto::Astrobj::Generic::processHitQuantities ( Photon ph,
double *  coord_ph_hit,
double *  coord_obj_hit,
double  dt,
Astrobj::Properties data 
) const
virtualinherited

processHitQuantities fills the requested data in Impact. To use it, you need to call it in the Impact() method for your object in case of hit. It will fill Redshift, Intensity, Spectrum, BinSpectrum and update the Photon's transmission by calling Photon::transmi(), only if data==NULL.

You can overload it for your Astrobj. The generic implementation calls emission(), integrateEmission() and transmission() below.

void Gyoto::Astrobj::Generic::setFlag_radtransf ( int  flag)
inherited

Set whether the object is optically thin.

Set flag indicating that radiative transfer should be integrated, i.e. the object is to be considered optically thin.

Parameters
flag,:1 if optically thin, 0 if optically thick.
virtual void Gyoto::Astrobj::Generic::setMetric ( SmartPointer< Metric::Generic )
virtualinherited
virtual int Gyoto::Astrobj::Standard::setParameter ( std::string  name,
std::string  content 
)
virtual

Called from setParameters()

 Assume MyKind is a sublcass of Astrobj::Generic which has towo
 members (a string StringMember and a double DoubleMember):
int MyKind::setParameter(std::string name, std::string content) {
if (name=="StringMember") setStringMember(content);
else if (name=="DoubleMember") setDoubleMemeber(atof(content.c_str()));
else return Generic::setParameter(name, content);
return 0;
}

If MyKind is not a direct subclass of Generic but is a subclass of e.g. Standard, UniformSphere of ThinDisk, it should call the corresponding setParameter() implementation instead of Generic::setParameter().

Parameters
nameXML name of the parameter
contentstring representation of the value
Returns
0 if this parameter is known, 1 if it is not.

Reimplemented from Gyoto::Astrobj::Generic.

Reimplemented in Gyoto::Astrobj::Star, Gyoto::Astrobj::UniformSphere, Gyoto::Astrobj::Torus, and Gyoto::Astrobj::FixedStar.

virtual void Gyoto::Astrobj::Generic::setParameters ( FactoryMessenger fmp)
virtualinherited

Main loop in Subcontractor_t function.

 The Subcontractor_t function for each Astrobj kind should look
 somewhat like this:
SmartPointer<Astrobj::Generic>
Gyoto::Astrobj::MyKind::Subcontractor(FactoryMessenger* fmp) {
SmartPointer<MyKind> ao = new MyKind();
ao -> setParameters(fmp);
return ao;
}
 Each object kind should implement setParameter(string name,
 string content) to interpret the individual XML
 elements. setParameters() can be overloaded in case the specific
 Astrobj class needs low level access to the FactoryMessenger. See
 UniformSphere::setParameters().

Reimplemented in Gyoto::Astrobj::PatternDisk, Gyoto::Astrobj::Disk3D, Gyoto::Astrobj::Star, Gyoto::Astrobj::UniformSphere, Gyoto::Astrobj::Complex, and Gyoto::Astrobj::Torus.

virtual void Gyoto::Astrobj::Generic::setRmax ( double  val)
virtualinherited

Set maximal distance from center of coordinate system.

Set maximal distance from center of coordinate system at which a Photon may hit the object.

Side effect: set rmax_set_ to 1.

virtual double Gyoto::Astrobj::Generic::transmission ( double  nuem,
double  dsem,
double  coord[8] 
) const
virtualinherited

Transmission: exp( {} * dsem )

transmission() computes the transmission of this fluid element or 0 if optically thick. The default implementation returns 1. (no attenuation) if optically thin, 0. if optically thick.

Parameters
nuemfrequency in the fluid's frame
coordPhoton coordinate
dsemgeometrical length in geometrical units

Reimplemented in Gyoto::Astrobj::PatternDisk, and Gyoto::Astrobj::Torus.

virtual void Gyoto::Astrobj::Generic::unsetRmax ( )
virtualinherited

Set rmax_set_ to 0.

getRmax() will then be free to recompute rmax_. Astrobjs which cache rmax_ may need to update it when unsetRmax() is called.

Reimplemented in Gyoto::Astrobj::Star.

Member Data Documentation

SmartPointer<Gyoto::Metric::Generic> Gyoto::Astrobj::Generic::gg_
protectedinherited

The Metric in this end of the Universe

const std::string Gyoto::Astrobj::Generic::kind_
protectedinherited

Kind of object (e.g. "Star"...)

The kind should match the name of the class, e.g. "Star" for a Gyoto::Star.

double Gyoto::Astrobj::Generic::rmax_
protectedinherited

Maximum distance to the center of the coordinate system.

Maximum distance from the center of the coordinate system at which a photon may hit the object. Child classes may choose to update rmax at all time or to use it to cache the value, for instance when getRmax() is called. External classes (Photons in particular) must use getRmax() to access this information.

rmax_set_==1 means that rmax_ was set using setRmax() or the constructor. In this case, getRmax() must always return this value, not recompute it.

int Gyoto::Astrobj::Generic::rmax_set_
protectedinherited

Never recompute rmax: it was externally set.

rmax_set_==1 means that rmax_ was set using setRmax() or the constructor. In this case, getRmax() must always return this value, not recompute it.

Use unsetRmax() to reset rmax_set_ to 0.


The documentation for this class was generated from the following file: