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java.lang.Object uk.ac.starlink.ast.AstObject uk.ac.starlink.ast.Mapping uk.ac.starlink.ast.SpecMap
public class SpecMap
Java interface to the AST SpecMap class  sequence of spectral coordinate conversions. A SpecMap is a specialised form of Mapping which can be used to represent a sequence of conversions between standard spectral coordinate systems.
When an SpecMap is first created, it simply performs a unit (null) Mapping. Using the astSpecAdd function, a series of coordinate conversion steps may then be added. This allows multistep conversions between a variety of spectral coordinate systems to be assembled out of a set of building blocks.
Conversions are available to transform between standards of rest. Such conversions need to know the source position as an RA and DEC. This information can be supplied in the form of parameters for the relevant conversions, in which case the SpecMap is 1dimensional, simply transforming the spectral axis values. This means that the same source position will always be used by the SpecMap. However, this may not be appropriate for an accurate description of a 3D spectral cube, where changes of spatial position can produce significant changes in the Doppler shift introduced when transforming between standards of rest. For this situation, a 3dimensional SpecMap can be created in which axes 2 and 3 correspond to the source RA and DEC The SpecMap simply copies values for axes 2 and 3 from input to output), but modifies axis 1 values (the spectral axis) appropriately.
For details of the individual coordinate conversions available, see the description of the astSpecAdd function.
This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public Licence for more details.
You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 021101301, USA
Nested Class Summary 

Nested classes/interfaces inherited from class uk.ac.starlink.ast.Mapping 

Mapping.Interpolator, Mapping.Spreader 
Field Summary 

Fields inherited from class uk.ac.starlink.ast.Mapping 

LINEAR_INTERPOLATOR, LINEAR_SPREADER, NEAREST_INTERPOLATOR, NEAREST_SPREADER 
Fields inherited from class uk.ac.starlink.ast.AstObject 

AST__BAD, AST__TUNULL, pointer 
Constructor Summary  

SpecMap(int nin,
int flags)
Creates a SpecMap. 
Method Summary  

void 
specAdd(String cvt,
double[] args)
Add a spectral coordinate conversion to a SpecMap. 
Methods inherited from class uk.ac.starlink.ast.Mapping 

decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP 
Methods inherited from class uk.ac.starlink.ast.AstObject 

annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune 
Methods inherited from class java.lang.Object 

clone, getClass, notify, notifyAll, toString, wait, wait, wait 
Constructor Detail 

public SpecMap(int nin, int flags)
nin
 The number of inputs to the Mapping (this will also equal the
number of outputs). This value must be either 1 or 3. In either
case, the first input and output correspoindis the spectral axis.
For a 3axis SpecMap, the second and third axes give the RA and
DEC (J2000 FK5) of the source. This positional information is
used by conversions which transform between standards of rest,
and replaces the "RA" and "DEC" arguments for the individual
conversions listed in description of the "SpecAdd"
function.flags
 This parameter is reserved for future use and should currently
always be set to zero.
AstException
 if an error occurred in the AST libraryspecAdd(java.lang.String, double[])
Method Detail 

public void specAdd(String cvt, double[] args)
When a SpecMap is first created (using astSpecMap), it simply performs a unit (null) Mapping. By using astSpecAdd (repeatedly if necessary), one or more coordinate conversion steps may then be added, which the SpecMap will perform in sequence. This allows multistep conversions between a variety of spectral coordinate systems to be assembled out of the building blocks provided by this class.
Normally, if a SpecMap's Invert attribute is zero (the default), then its forward transformation is performed by carrying out each of the individual coordinate conversions specified by astSpecAdd in the order given (i.e. with the most recently added conversion applied last).
This order is reversed if the SpecMap's Invert attribute is nonzero (or if the inverse transformation is requested by any other means) and each individual coordinate conversion is also replaced by its own inverse. This process inverts the overall effect of the SpecMap. In this case, the first conversion to be applied would be the inverse of the one most recently added.
 "FRTOVL" (RF): Convert frequency to relativistic velocity.
 "VLTOFR" (RF): Convert relativistic velocity to Frequency.
 "ENTOFR": Convert energy to frequency.
 "FRTOEN": Convert frequency to energy.
 "WNTOFR": Convert wave number to frequency.
 "FRTOWN": Convert frequency to wave number.
 "WVTOFR": Convert wavelength (vacuum) to frequency.
 "FRTOWV": Convert frequency to wavelength (vacuum).
 "AWTOFR": Convert wavelength (air) to frequency.
 "FRTOAW": Convert frequency to wavelength (air).
 "VRTOVL": Convert radio to relativistic velocity.
 "VLTOVR": Convert relativistic to radio velocity.
 "VOTOVL": Convert optical to relativistic velocity.
 "VLTOVO": Convert relativistic to optical velocity.
 "ZOTOVL": Convert redshift to relativistic velocity.
 "VLTOZO": Convert relativistic velocity to redshift.
 "BTTOVL": Convert beta factor to relativistic velocity.
 "VLTOBT": Convert relativistic velocity to beta factor.
 "USF2HL" (VOFF,RA,DEC): Convert frequency from a userdefined
reference frame to heliocentric.
 "HLF2US" (VOFF,RA,DEC): Convert frequency from heliocentric
reference frame to userdefined.
 "TPF2HL" (OBSLON,OBSLAT,OBSALT,EPOCH,RA,DEC): Convert frequency from
topocentric reference frame to heliocentric.
 "HLF2TP" (OBSLON,OBSLAT,OBSALT,EPOCH,RA,DEC): Convert frequency from
heliocentric reference frame to topocentric.
 "GEF2HL" (EPOCH,RA,DEC): Convert frequency from geocentric
reference frame to heliocentric.
 "HLF2GE" (EPOCH,RA,DEC): Convert frequency from
heliocentric reference frame to geocentric.
 "BYF2HL" (EPOCH,RA,DEC): Convert frequency from
barycentric reference frame to heliocentric.
 "HLF2BY" (EPOCH,RA,DEC): Convert frequency from
heliocentric reference frame to barycentric.
 "LKF2HL" (RA,DEC): Convert frequency from kinematic LSR
reference frame to heliocentric.
 "HLF2LK" (RA,DEC): Convert frequency from heliocentric
reference frame to kinematic LSR.
 "LDF2HL" (RA,DEC): Convert frequency from dynamical LSR
reference frame to heliocentric.
 "HLF2LD" (RA,DEC): Convert frequency from heliocentric
reference frame to dynamical LSR.
 "LGF2HL" (RA,DEC): Convert frequency from local group
reference frame to heliocentric.
 "HLF2LG" (RA,DEC): Convert frequency from heliocentric
reference frame to local group.
 "GLF2HL" (RA,DEC): Convert frequency from galactic
reference frame to heliocentric.
 "HLF2GL" (RA,DEC): Convert frequency from heliocentric
reference frame to galactic.
The units for the values processed by the above conversions are as follows:
 all velocities: metres per second (positive if the source receeds from
the observer).
 frequency: Hertz.
 all wavelengths: metres.
 energy: Joules.
 wave number: cycles per metre.
The arguments used in the above conversions are as follows:
 RF: Rest frequency (Hz).
 OBSALT: Geodetic altitude of observer (IAU 1975, metres).
 OBSLAT: Geodetic latitude of observer (IAU 1975, radians).
 OBSLON: Longitude of observer (radians  positive eastwards).
 EPOCH: Epoch of observation (UT1 expressed as a Modified Julian Date).
 RA: Right Ascension of source (radians, FK5 J2000).
 DEC: Declination of source (radians, FK5 J2000).
 VOFF: Velocity of the userdefined reference frame, towards the
position given by RA and DEC, measured in the heliocentric
reference frame.
If the SpecMap is 3dimensional, source positions are provided by the values supplied to inputs 2 and 3 of the SpecMap (which are simply copied to outputs 2 and 3). Note, usable values are still required for the RA and DEC arguments in order to define the "userdefined" reference frame used by USF2HL and HLF2US. However, AST__BAD can be supplied for RA and DEC if the userdefined reference frame is not required.
cvt
 Pointer to a nullterminated string which identifies the
spectral coordinate conversion to be added to the
SpecMap. See the "Available Conversions" section for details of
those available.args
 An array containing argument values for the spectral
coordinate conversion. The number of arguments required, and
hence the number of array elements used, depends on the
conversion specified (see the "Available Conversions"
section). This array is ignored
and a NULL pointer may be supplied
if no arguments are needed.
AstException
 if an error occurred in the AST library


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