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casacore
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casacore
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TaQL user defined functions handling measures. More...
Modules | |
| MeasUDF_module_internal_classes | |
| Internal MeasUDF_module classes and functions. | |
Classes | |
| class | casacore::BaseEngine |
| Abstract base class for the TaQL UDF conversion engines. More... | |
| class | casacore::DirectionEngine |
| Engine for TaQL UDF Direction conversions. More... | |
| class | casacore::DirectionUDF |
| TaQL UDFs for Direction conversions. More... | |
| class | casacore::DopplerEngine |
| Engine for TaQL UDF Doppler conversions. More... | |
| class | casacore::DopplerUDF |
| TaQL UDFs for Doppler conversions. More... | |
| class | casacore::EarthMagneticEngine |
| Engine for TaQL UDF EarthMagnetic conversions. More... | |
| class | casacore::EarthMagneticUDF |
| TaQL UDFs for EarthMagnetic conversions. More... | |
| class | casacore::EpochEngine |
| Engine for TaQL UDF Epoch conversions. More... | |
| class | casacore::EpochUDF |
| TaQL UDFs for Epoch conversions. More... | |
| class | casacore::FrequencyEngine |
| Engine for TaQL UDF Frequency conversions. More... | |
| class | casacore::FrequencyUDF |
| TaQL UDFs for Frequency conversions. More... | |
| class | casacore::MeasEngine< M > |
| Templated base class for the TaQL UDF conversion engines. More... | |
| class | casacore::PositionEngine |
| Engine for TaQL UDF Position conversions. More... | |
| class | casacore::PositionUDF |
| TaQL UDFs for Position conversions. More... | |
| class | casacore::RadialVelocityEngine |
| Engine for TaQL UDF RadialVelocity conversions. More... | |
| class | casacore::RadialVelocityUDF |
| TaQL UDFs for RadialVelocity conversions. More... | |
TaQL user defined functions handling measures.
See below for an overview of the classes in this module.
This module extends TaQL (the Table Query Language) with functions handling measures. Currently it can handle MDirection, MEpoch, MPosition, MFrequency, MRadialVelocity, MDoppler and MEarthMagnetic.
These functions make it possible to convert one or more measures from one reference type and frame to another. For example, to convert a direction from J2000 to apparent one can specify the direction in J2000 as well as a time and position to define the measure frame like:
The above example converts the given J2000 direction to apparent coordinates for the given time (current time is used) and for all positions in the POSITION column in the given ANTENNA table.
As shown in the example an argument of a meas function can be a constant, a table column in a table. or any expression. If a table column is given, it is recognized if the column has a reference type attached to it (using the TableMeasures). In this example it would be recognized that the positions in the POSITION column are given as, say, WGS84.
For constants the reference type can be given in case it differs from the default type. In the example UTC is specified for the time (was not necessary because it is the default).
Note: The meas library will be loaded dynamically by TaQL when such a function is used; Therefore it is important that the library and the other casacore libraries are built shared;
It is also important that the library can be found in the (DY)LD_LIBRARY_PATH;
It is very handy to be able to convert measures in tools that deal with various table columns (e.g. TaQL, TablePlot, pyrap).
1.8.5
