HealPix projection class interface definition. More...

#include <GHealpix.hpp>

Inheritance diagram for GHealpix:

Public Member Functions
	GHealpix (void)
	Void constructor. More...

	GHealpix (const int &nside, const std::string &ordering="NESTED", const std::string &coordsys="CEL")
	Constructor. More...

	GHealpix (const GFitsHDU &hdu)
	Constructor from FITS HDU table. More...

	GHealpix (const GHealpix &wcs)
	Copy constructor. More...

virtual	~GHealpix (void)
	Destructor. More...

GHealpix &	operator= (const GHealpix &wcs)
	Assignment operator. More...

virtual void	clear (void)
	Clear object. More...

virtual GHealpix *	clone (void) const
	Clone instance. More...

virtual std::string	classname (void) const
	Return class name. More...

virtual int	size (void) const
	Return dimension of projection. More...

virtual std::string	code (void) const
	Return projection code. More...

virtual std::string	name (void) const
	Return projection name. More...

virtual void	read (const GFitsHDU &hdu)
	Read Healpix definition from FITS header. More...

virtual void	write (GFitsHDU &hdu) const
	Write Healpix definition into FITS HDU. More...

virtual double	solidangle (const GSkyPixel &pixel) const
	Returns solid angle of pixel. More...

virtual GSkyDir	pix2dir (const GSkyPixel &pixel) const
	Returns sky direction of pixel. More...

virtual GSkyPixel	dir2pix (const GSkyDir &dir) const
	Returns sky map pixel of sky coordinate. More...

virtual GBilinear	interpolator (const GSkyDir &dir) const
	Return interpolator for given sky direction. More...

virtual std::string	print (const GChatter &chatter=NORMAL) const
	Print WCS information. More...

const int &	npix (void) const
	Returns number of pixels. More...

const int &	nside (void) const
	Returns number of divisions of the side of each base pixel. More...

std::string	ordering (void) const
	Returns ordering parameter. More...

void	ordering (const std::string &ordering)
	Set pixel ordering. More...

std::vector< int >	neighbours (const GSkyPixel &pixel) const
	Return neighbouring pixels of a pixel. More...

GSkyDirs	boundaries (const GSkyPixel &pixel, const int &step=1) const
	Return pixel boundaries. More...

double	max_pixrad (void) const
	Return maximum angular distance between pixel centre and corners. More...

Public Member Functions inherited from GSkyProjection
	GSkyProjection (void)
	Void constructor. More...

	GSkyProjection (const GSkyProjection &proj)
	Copy constructor. More...

virtual	~GSkyProjection (void)
	Destructor. More...

virtual GSkyProjection &	operator= (const GSkyProjection &proj)
	Assignment operator. More...

virtual std::string	coordsys (void) const
	Returns coordinate system. More...

virtual void	coordsys (const std::string &coordsys)
	Set coordinate system. More...

Public Member Functions inherited from GBase
virtual	~GBase (void)
	Destructor. More...

Private Member Functions
void	init_members (void)
	Initialise class members. More...

void	copy_members (const GHealpix &wcs)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

virtual bool	compare (const GSkyProjection &proj) const
	Returns true if argument is identical. More...

int	compress_bits (const int &value) const
	Compress Bits. More...

int	spread_bits (const int &value) const
	Spread Bits. More...

void	pix2xyf (const int &pix, int ix, int iy, int *face) const
	Convert pixel number in to (x,y,face) tuple. More...

void	nest2xyf (const int &pix, int ix, int iy, int *face) const
	Convert pixel number in nested scheme to (x,y,face) tuple. More...

void	ring2xyf (const int &pix, int ix, int iy, int *face) const
	Convert pixel number in ring scheme to (x,y,face) tuple. More...

int	xyf2nest (const int &ix, const int &iy, const int &face) const
	Convert (x,y,face) tuple to pixel number in nested scheme. More...

int	xyf2ring (const int &ix, const int &iy, const int &face) const
	Convert (x,y,face) tuple to pixel number in ring scheme. More...

void	xyf2loc (const double &x, const double &y, const int &face, double z, double phi) const
	Convert (x,y,f) tuple into local coordinates. More...

int	nside2order (const int &nside) const
	Convert nside to order. More...

int	nest2ring (const int &pix) const
	Converts pixel number in nested indexing scheme to ring scheme. More...

int	ring2nest (const int &pix) const
	Converts pixel number in ring indexing scheme to nested scheme. More...

void	pix2xy (const int &ipix, int x, int y) const
	Convert pixel index to (x,y) coordinate. More...

int	xy2pix (int x, int y) const
	Convert (x,y) coordinate to pixel. More...

void	pix2ang_ring (int ipix, double theta, double phi) const
	Convert pixel index to (theta,phi) angles for ring ordering. More...

void	pix2ang_nest (int ipix, double theta, double phi) const
	Convert pixel index to (theta,phi) angles for nested ordering. More...

int	ang2pix_z_phi_ring (double z, double phi) const
	Returns pixel which contains angular coordinates (z,phi) More...

int	ang2pix_z_phi_nest (double z, double phi) const
	Returns pixel which contains angular coordinates (z,phi) More...

int	ring_above (const double &z) const
	Get ring index north of cos(theta) More...

void	get_ring_info (const int &ring, int startpix, int ringpix, bool *shifted) const
	Returns useful information about a given ring of the projection. More...

void	get_ring_info (const int &ring, int startpix, int ringpix, double theta, bool shifted) const
	Returns useful information about a given ring of the projection. More...

GBilinear	interpolator (const double &theta, const double &phi) const
	Return interpolator. More...

unsigned int	isqrt (unsigned int arg) const
	Integer n that fulfills nn <= arg < (n+1)(n+1) More...

GVector	set_z_phi (const double &z, const double &phi) const
	Return 3D vector. More...

GSkyDir	loc2dir (const double &z, const double &phi) const
	Convert local coordinate into sky direction. More...

Private Attributes
int	m_nside
	Number of divisions of each base pixel (1-8192) More...

int	m_npface

int	m_ncap
	Number of pixels in polar cap. More...

int	m_order
	Order. More...

int	m_ordering
	Pixel ordering (0=ring, 1=nested, -1=?) More...

int	m_num_pixels
	Number of pixels in projection. More...

double	m_fact1

double	m_fact2

double	m_solidangle
	Solid angle of pixel. More...

Additional Inherited Members
Protected Member Functions inherited from GSkyProjection
void	init_members (void)
	Initialise class members. More...

void	copy_members (const GSkyProjection &proj)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

Protected Attributes inherited from GSkyProjection
int	m_coordsys
	0=CEL, 1=GAL More...

Detailed Description

HealPix projection class interface definition.

The HealPix projection class has been implemented by adapting code from the HealPix library (version 2.1). For more information about HEALPix, see http://healpix.jpl.nasa.gov

Definition at line 50 of file GHealpix.hpp.

Constructor & Destructor Documentation

GHealpix::GHealpix ( void )

Void constructor.

Definition at line 103 of file GHealpix.cpp.

References init_members().

Referenced by clone().

GHealpix::GHealpix	(	const int &	nside,
		const std::string &	order = `"NESTED"`,
		const std::string &	coords = `"CEL"`
	)

Constructor.

Parameters

[in]	nside	Number of sides.
[in]	order	Pixel ordering ('RING' or 'NESTED').
[in]	coords	Coordinate system ('CEL' or 'GAL').

Exceptions

GException::invalid_argument Invalid nside parameter.

Definition at line 123 of file GHealpix.cpp.

References GSkyProjection::coordsys(), gammalib::fourpi, G_CONSTRUCT, init_members(), m_fact1, m_fact2, m_ncap, m_npface, m_nside, m_num_pixels, m_order, m_solidangle, nside(), nside2order(), ordering(), and gammalib::str().

GHealpix::GHealpix ( const GFitsHDU & hdu )

explicit

Constructor from FITS HDU table.

Parameters

[in] hdu FITS HDU.

Definition at line 164 of file GHealpix.cpp.

References init_members(), and read().

GHealpix::GHealpix ( const GHealpix & proj )

Copy constructor.

Parameters

[in] proj Healpix projection.

Definition at line 182 of file GHealpix.cpp.

References copy_members(), and init_members().

GHealpix::~GHealpix ( void )

virtual

Destructor.

Definition at line 198 of file GHealpix.cpp.

References free_members().

Member Function Documentation

int GHealpix::ang2pix_z_phi_nest	(	double	z,
		double	phi
	)		const

private

Returns pixel which contains angular coordinates (z,phi)

Parameters

[in]	z	Cosine of zenith angle - cos(theta).
[in]	phi	Azimuth angle in radians.

Definition at line 1568 of file GHealpix.cpp.

References gammalib::inv_pihalf, m_order, gammalib::modulo(), ns_max, order_max, sqrt(), gammalib::twopi, gammalib::twothird, and xy2pix().

Referenced by dir2pix().

int GHealpix::ang2pix_z_phi_ring	(	double	z,
		double	phi
	)		const

private

Returns pixel which contains angular coordinates (z,phi)

Parameters

[in]	z	Cosine of zenith angle - cos(theta).
[in]	phi	Azimuth angle in radians.

Definition at line 1520 of file GHealpix.cpp.

References gammalib::inv_pihalf, m_ncap, m_nside, m_num_pixels, gammalib::modulo(), sqrt(), gammalib::twopi, and gammalib::twothird.

Referenced by dir2pix().

GSkyDirs GHealpix::boundaries	(	const GSkyPixel &	pixel,
		const int &	step = `1`
	)		const

Return pixel boundaries.

Parameters

[in]	pixel	Sky pixel.
[in]	step	Number of returned points (4*step, defaults to 4).

Returns: Array of pixel boundaries.

The method returns a container of sky directions along the boundary of a HealPix pixel. By default, the 4 corners of HealPix pixel will be returned. The first point corresponds to the northernmost corner, the subsequent points follow the pixel boundary through west, south and east corners. If step>1 more intermediate points will be added after the 4th corner of the pixel.

This method has been adapted from the boundaries() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 711 of file GHealpix.cpp.

References GSkyDirs::append(), G_BOUNDARIES, GSkyPixel::is_1D(), loc2dir(), m_nside, pix2xyf(), GSkyPixel::print(), and xyf2loc().

Referenced by GSkyMap::flux().

std::string GHealpix::classname ( void ) const

inlinevirtual

Return class name.

Returns: String containing the class name ("GHealpix").

Implements GSkyProjection.

Definition at line 144 of file GHealpix.hpp.

void GHealpix::clear ( void )

virtual

Clear object.

This method properly resets the object to an initial state.

Implements GSkyProjection.

Definition at line 255 of file GHealpix.cpp.

References GSkyProjection::free_members(), free_members(), GSkyProjection::init_members(), and init_members().

Referenced by read().

GHealpix * GHealpix::clone ( void ) const

virtual

Clone instance.

Implements GSkyProjection.

Definition at line 273 of file GHealpix.cpp.

References GHealpix().

std::string GHealpix::code ( void ) const

inlinevirtual

Return projection code.

Returns: Projection code.

Returns the projection code "HPX".

Implements GSkyProjection.

Definition at line 172 of file GHealpix.hpp.

bool GHealpix::compare ( const GSkyProjection & proj ) const

privatevirtual

Returns true if argument is identical.

Parameters

[in] proj Sky projection.

This method is a helper for the sky projection friends.

Implements GSkyProjection.

Definition at line 914 of file GHealpix.cpp.

References GSkyProjection::m_coordsys, m_ncap, m_npface, m_nside, m_num_pixels, m_order, and m_ordering.

int GHealpix::compress_bits ( const int & value ) const

private

Compress Bits.

Parameters

[in] value Value.

Returns: Compressed Bits.

This method has been adapted from the compress_bits() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 952 of file GHealpix.cpp.

References ctab.

Referenced by nest2xyf().

void GHealpix::copy_members ( const GHealpix & proj )

private

Copy class members.

Parameters

[in] proj Healpix projection.

Definition at line 879 of file GHealpix.cpp.

References m_fact1, m_fact2, m_ncap, m_npface, m_nside, m_num_pixels, m_order, m_ordering, and m_solidangle.

Referenced by GHealpix(), and operator=().

GSkyPixel GHealpix::dir2pix ( const GSkyDir & dir ) const

virtual

Returns sky map pixel of sky coordinate.

Parameters

[in] dir Sky coordinate.

Returns: Sky map pixel.

Implements GSkyProjection.

Definition at line 433 of file GHealpix.cpp.

References ang2pix_z_phi_nest(), ang2pix_z_phi_ring(), GSkyDir::b(), cos(), GSkyDir::dec(), GSkyDir::l(), GSkyProjection::m_coordsys, m_ordering, gammalib::pihalf, and GSkyDir::ra().

void GHealpix::free_members ( void )

private

Delete class members.

Definition at line 900 of file GHealpix.cpp.

Referenced by clear(), operator=(), and ~GHealpix().

void GHealpix::get_ring_info	(	const int &	ring,
		int *	startpix,
		int *	ringpix,
		bool *	shifted
	)		const

private

Returns useful information about a given ring of the projection.

Parameters

[in]	ring	The ring number (the number of the first ring is 1)
[out]	startpix	The number of the first pixel in the ring
[out]	ringpix	The number of pixels in the ring
[out]	shifted	If true, the center of the first pixel is not at phi=0

This method has been adapted from the get_ring_info_small() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1674 of file GHealpix.cpp.

References m_ncap, m_nside, and m_num_pixels.

Referenced by interpolator(), and xyf2ring().

void GHealpix::get_ring_info	(	const int &	ring,
		int *	startpix,
		int *	ringpix,
		double *	theta,
		bool *	shifted
	)		const

private

Returns useful information about a given ring of the projection.

Parameters

[in]	ring	The ring number (the number of the first ring is 1)
[out]	startpix	The number of the first pixel in the ring
[out]	ringpix	The number of pixels in the ring
[out]	theta	(radians)
[out]	shifted	If true, the center of the first pixel is not at phi=0

This method has been adapted from the get_ring_info2() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1719 of file GHealpix.cpp.

References gammalib::acos(), gammalib::atan2(), m_fact1, m_fact2, m_ncap, m_nside, m_num_pixels, gammalib::pi, and sqrt().

void GHealpix::init_members ( void )

private

Initialise class members.

Definition at line 846 of file GHealpix.cpp.

References ctab, m_fact1, m_fact2, m_ncap, m_npface, m_nside, m_num_pixels, m_order, m_ordering, m_solidangle, and utab.

Referenced by clear(), GHealpix(), and operator=().

GBilinear GHealpix::interpolator ( const GSkyDir & dir ) const

virtual

Return interpolator for given sky direction.

Parameters

[in] dir Sky direction

Definition at line 474 of file GHealpix.cpp.

References GSkyDir::b(), GSkyDir::dec(), GSkyDir::l(), GSkyProjection::m_coordsys, gammalib::modulo(), gammalib::pi, gammalib::pihalf, GSkyDir::ra(), and gammalib::twopi.

Referenced by interpolator().

GBilinear GHealpix::interpolator	(	const double &	theta,
		const double &	phi
	)		const

private

Return interpolator.

Parameters

[in]	theta	Colatitude of direction (radian, the North pole is at theta=0)
[in]	phi	Longitude of direction (radians)

Exceptions

GException::invalid_argument Invalid theta argument

Returns a bilinear pixel interpolator for a given sky direction.

This method has been adapted from the get_interpol() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1770 of file GHealpix.cpp.

References cos(), G_INTERPOLATOR, get_ring_info(), GBilinear::index1(), GBilinear::index2(), GBilinear::index3(), GBilinear::index4(), interpolator(), m_nside, m_num_pixels, m_ordering, gammalib::pi, ring2nest(), ring_above(), gammalib::str(), gammalib::twopi, GBilinear::weight1(), GBilinear::weight2(), GBilinear::weight3(), and GBilinear::weight4().

unsigned int GHealpix::isqrt ( unsigned int arg ) const

private

Integer n that fulfills n*n <= arg < (n+1)*(n+1)

Parameters

[in] arg Argument.

Returns the integer n, which fulfills n*n <= arg < (n+1)*(n+1).

Definition at line 1893 of file GHealpix.cpp.

References sqrt().

Referenced by pix2ang_ring(), and ring2xyf().

GSkyDir GHealpix::loc2dir	(	const double &	z,
		const double &	phi
	)		const

private

Convert local coordinate into sky direction.

Parameters

[in]	z	Z value.
[in]	phi	Phi value.

Returns: Sky direction.

This method has been adapted from the locToVec3() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1237 of file GHealpix.cpp.

References asin(), gammalib::atan2(), cos(), GSkyDir::lb(), GSkyProjection::m_coordsys, GSkyDir::radec(), sin(), and sqrt().

Referenced by boundaries().

double GHealpix::max_pixrad ( void ) const

Return maximum angular distance between pixel centre and corners.

Returns: Maximum angular distance between pixel centre and corners (radians).

Returns the maximum angular distance (in radians) between any pixel centre and its corners.

This method has been adapted from the max_pixrad() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 778 of file GHealpix.cpp.

References angle(), gammalib::atan2(), cross(), m_nside, norm(), gammalib::pi, and set_z_phi().

std::string GHealpix::name ( void ) const

inlinevirtual

Return projection name.

Returns: Projection name.

Returns the projection name.

Implements GSkyProjection.

Definition at line 186 of file GHealpix.hpp.

std::vector< int > GHealpix::neighbours ( const GSkyPixel & pixel ) const

Return neighbouring pixels of a pixel.

Parameters

[in] pixel Pixel index.

Returns: Array of neighbouring pixels.

Returns the 8 neighbours of a given pixel. The method returns a vector with contains the pixel indices of the SW, W, NW, N, NE, E, SE and S neighbours of pix (in the given order). If a neighbour does not exist (this can only be the case for the W, N, E and S neighbors), its entry is set to -1.

This method has been adapted from the neighbors() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 579 of file GHealpix.cpp.

References G_NEIGHBOURS, GSkyPixel::is_1D(), m_nside, m_order, m_ordering, nb_facearray, nb_swaparray, nb_xoffset, nb_yoffset, pix2xyf(), GSkyPixel::print(), spread_bits(), xyf2nest(), and xyf2ring().

int GHealpix::nest2ring ( const int & pix ) const

private

Converts pixel number in nested indexing scheme to ring scheme.

Parameters

[in] pix Pixel number in nested indexing scheme.

Returns: Pixel number in ring indexing scheme.

Exceptions

GException::invalid_value Healpix projection does not represent a hiearachical map.

This method has been adapted from the nest2ring() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1301 of file GHealpix.cpp.

References G_NEST2RING, m_order, nest2xyf(), and xyf2ring().

void GHealpix::nest2xyf	(	const int &	pix,
		int *	ix,
		int *	iy,
		int *	face
	)		const

private

Convert pixel number in nested scheme to (x,y,face) tuple.

Parameters

[in]	pix	Pixel number in nested scheme.
[out]	ix	X index.
[out]	iy	Y index.
[out]	face	Face number.

This method has been adapted from the nest2xyf() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1021 of file GHealpix.cpp.

References compress_bits(), m_npface, and m_order.

Referenced by nest2ring(), and pix2xyf().

const int & GHealpix::npix ( void ) const

inline

Returns number of pixels.

Definition at line 196 of file GHealpix.hpp.

References m_num_pixels.

Referenced by GSkyMap::GSkyMap(), GSkyMap::is_same(), and write().

const int & GHealpix::nside ( void ) const

inline

Returns number of divisions of the side of each base pixel.

Definition at line 207 of file GHealpix.hpp.

References m_nside.

Referenced by GHealpix(), GSkyMap::is_same(), and write().

int GHealpix::nside2order ( const int & nside ) const

private

Convert nside to order.

Parameters

[in] nside Number of sides.

Returns: Order of HealPix projection.

Definition at line 1268 of file GHealpix.cpp.

References order_max.

Referenced by GHealpix(), and read().

GHealpix & GHealpix::operator= ( const GHealpix & proj )

Assignment operator.

Parameters

[in] proj Healpix projection.

Returns: Healpix projection.

Definition at line 220 of file GHealpix.cpp.

References copy_members(), free_members(), init_members(), and GSkyProjection::operator=().

std::string GHealpix::ordering ( void ) const

Returns ordering parameter.

Definition at line 511 of file GHealpix.cpp.

References m_ordering.

Referenced by GHealpix(), GSkyMap::is_same(), print(), read(), and write().

void GHealpix::ordering ( const std::string & ordering )

Set pixel ordering.

Parameters

[in] ordering Pixel ordering (RING or NEST/NESTED).

Exceptions

GException::invalid_argument Invalid ordering parameter.

Definition at line 540 of file GHealpix.cpp.

References G_ORDERING_SET, m_ordering, and gammalib::toupper().

void GHealpix::pix2ang_nest	(	int	ipix,
		double *	theta,
		double *	phi
	)		const

private

Convert pixel index to (theta,phi) angles for nested ordering.

Parameters

[in]	ipix	Pixel index [0,...,m_num_pixels[.
[out]	theta	Pointer to result zenith angle in radians.
[out]	phi	Pointer to result azimuth angle in radians.

Exceptions

GException::out_of_range Pixel index is out of range.

Definition at line 1453 of file GHealpix.cpp.

References gammalib::acos(), G_PIX2ANG_NEST, jpll, jrll, m_fact1, m_fact2, m_npface, m_nside, m_num_pixels, m_order, gammalib::pihalf, and pix2xy().

Referenced by pix2dir().

void GHealpix::pix2ang_ring	(	int	ipix,
		double *	theta,
		double *	phi
	)		const

private

Convert pixel index to (theta,phi) angles for ring ordering.

Parameters

[in]	ipix	Pixel index [0,...,m_num_pixels[.
[out]	theta	Pointer to result zenith angle in radians.
[out]	phi	Pointer to result azimuth angle in radians.

Exceptions

GException::out_of_range Pixel index is out of range.

Definition at line 1402 of file GHealpix.cpp.

References gammalib::acos(), G_PIX2ANG_RING, isqrt(), m_fact1, m_fact2, m_ncap, m_nside, m_num_pixels, and gammalib::pi.

Referenced by pix2dir().

GSkyDir GHealpix::pix2dir ( const GSkyPixel & pixel ) const

virtual

Returns sky direction of pixel.

Parameters

[in] pixel Sky map pixel.

Implements GSkyProjection.

Definition at line 384 of file GHealpix.cpp.

References G_XY2DIR, GSkyPixel::is_1D(), GSkyDir::lb(), GSkyProjection::m_coordsys, m_ordering, gammalib::pihalf, pix2ang_nest(), pix2ang_ring(), GSkyPixel::print(), and GSkyDir::radec().

Referenced by GSkyMap::flux().

void GHealpix::pix2xy	(	const int &	ipix,
		int *	x,
		int *	y
	)		const

private

Convert pixel index to (x,y) coordinate.

Parameters

[in]	ipix	Pixel index for which (x,y) are to be computed.
[out]	x	Pointer to x coordinate.
[out]	y	Pointer to y coordinate.

Definition at line 1364 of file GHealpix.cpp.

References ctab.

Referenced by pix2ang_nest().

void GHealpix::pix2xyf	(	const int &	pix,
		int *	ix,
		int *	iy,
		int *	face
	)		const

private

Convert pixel number in to (x,y,face) tuple.

Parameters

[in]	pix	Pixel number.
[out]	ix	X index.
[out]	iy	Y index.
[out]	face	Face number.

This method has been adapted from the pix2xyf() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 993 of file GHealpix.cpp.

References m_ordering, nest2xyf(), and ring2xyf().

Referenced by boundaries(), and neighbours().

std::string GHealpix::print ( const GChatter & chatter = NORMAL ) const

virtual

Print WCS information.

Parameters

[in] chatter Chattiness (defaults to NORMAL).

Returns: String containing WCS information.

Implements GSkyProjection.

Definition at line 802 of file GHealpix.cpp.

References GSkyProjection::coordsys(), m_ncap, m_npface, m_nside, m_num_pixels, m_order, m_solidangle, ordering(), gammalib::parformat(), SILENT, and gammalib::str().

void GHealpix::read ( const GFitsHDU & hdu )

virtual

Read Healpix definition from FITS header.

Parameters

[in] hdu FITS HDU.

Exceptions

GException::invalid_argument Unable to load Healpix definition from HDU.

Implements GSkyProjection.

Definition at line 287 of file GHealpix.cpp.

References clear(), GSkyProjection::coordsys(), gammalib::fourpi, G_READ, GFitsHDU::has_card(), GFitsHDU::integer(), m_fact1, m_fact2, m_ncap, m_npface, m_nside, m_num_pixels, m_order, m_solidangle, nside2order(), ordering(), and GFitsHDU::string().

Referenced by GHealpix().

int GHealpix::ring2nest ( const int & pix ) const

private

Converts pixel number in ring indexing scheme to nested scheme.

Parameters

[in] pix Pixel number in ring indexing scheme.

Returns: Pixel number in nested indexing scheme.

Exceptions

GException::invalid_value Healpix projection does not represent a hiearachical map.

This method has been adapted from the ring2nest() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1335 of file GHealpix.cpp.

References G_RING2NEST, m_order, ring2xyf(), and xyf2nest().

Referenced by interpolator().

void GHealpix::ring2xyf	(	const int &	pix,
		int *	ix,
		int *	iy,
		int *	face
	)		const

private

Convert pixel number in ring scheme to (x,y,face) tuple.

Parameters

[in]	pix	Pixel number in ring scheme
[out]	ix	X index.
[out]	iy	Y index.
[out]	face	Face number.

This method has been adapted from the ring2xyf() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1049 of file GHealpix.cpp.

References isqrt(), jpll, jrll, m_ncap, m_nside, m_num_pixels, and m_order.

Referenced by pix2xyf(), and ring2nest().

int GHealpix::ring_above ( const double & costheta ) const

private

Get ring index north of cos(theta)

Parameters

[in] costheta Cosine of colatitude theta

Returns the number of the next ring to the north of cos(theta). It may return 0; in this case costheta lies north of all rings.

This method has been adapted from the ring_above() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 1636 of file GHealpix.cpp.

References abs(), m_nside, sqrt(), and gammalib::twothird.

Referenced by interpolator().

GVector GHealpix::set_z_phi	(	const double &	z,
		const double &	phi
	)		const

private

Return 3D vector.

Parameters

[in]	z	Z value.
[in]	phi	Phi value.

Returns: 3D vector

This method has been adapted from the set_z_phi() function located in the file vec3.h in Healpix version 3.20.

Definition at line 1910 of file GHealpix.cpp.

References cos(), sin(), and sqrt().

Referenced by max_pixrad().

int GHealpix::size ( void ) const

inlinevirtual

Return dimension of projection.

Returns: Dimension of projection.

Returns the dimension of the projection.

Implements GSkyProjection.

Definition at line 158 of file GHealpix.hpp.

double GHealpix::solidangle ( const GSkyPixel & pixel ) const

inlinevirtual

Returns solid angle of pixel.

Parameters

[in] pixel Sky pixel.

Returns: Solid angle of pixel.

Returns the solid angle of the specified pixel. Note that HEALPix pixels have all the same solid angle, hence the pixel argument is in fact not used by the method.

Implements GSkyProjection.

Definition at line 224 of file GHealpix.hpp.

References m_solidangle.

int GHealpix::spread_bits ( const int & value ) const

private

Spread Bits.

Parameters

[in] value Compressed value.

Returns: Spread Bits.

This method has been adapted from the spread_bits() function located in the file healpix_base.cc in Healpix version 3.20.

Definition at line 972 of file GHealpix.cpp.

References utab.

Referenced by neighbours(), and xyf2nest().

void GHealpix::write ( GFitsHDU & hdu ) const

virtual

Write Healpix definition into FITS HDU.

Parameters

[in] hdu FITS HDU.

Writes the following keywords in the FITS HDU: EXTNAME = HEALPIX PIXTYPE = HEALPIX NSIDE = nside() = m_nside FIRSTPIX = 0 LASTPIX = npix()-1 = m_num_pixels-1 ORDERING = ordering() COORDSYS = coordsys()

Implements GSkyProjection.

Definition at line 356 of file GHealpix.cpp.

References GFitsHDU::card(), GSkyProjection::coordsys(), GFitsHDU::extname(), npix(), nside(), and ordering().