casacore
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Modules | |
LEL_module_internal_classes | |
Internal LEL_module classes and functions. | |
Classes | |
class | casacore::LatticeExpr< T > |
Class to allow C++ expressions involving lattices. More... | |
class | casacore::LatticeExprNode |
Bridging class to allow C++ expressions involving lattices. More... | |
class | casacore::LELCoordinates |
Envelope class to handle Lattice Coordinates in LEL. More... | |
Lattice expressions.
See below for an overview of the classes in this module.
LEL: Lattice Expression Language.
A LatticeExpr represents a mathematical expression of lattices. All standard operators, regions, and many, many functions can be used in an expression.
An expression is calculated on-the-fly. Thus only when the user gets a part of the lattice, is the expression calculated for that part. Subexpressions resulting in a scalar are calculated only once, on a get of the first part of the lattice expression.
Note that a lattice expression is not writable, thus using the put function on such a lattice results in an exception.
Note 223 gives a more detailed explanation of the capabilities of LEL (Lattice Expression Language).
If the expression consists of images, the result can also be treated as an image using class ImageExpr . With the command
function in ImageExprParse it is possible to parse and execute a LEL expression given as as a string.