This LEL class handles numerical functions whose return type is a Double. More...

#include <LELFunction.h>

Inheritance diagram for casa::LELFunctionDouble:

Public Member Functions
	LELFunctionDouble (const LELFunctionEnums::Function function, const Block< LatticeExprNode > &expr)
	Constructor takes operation and left and right expressions to be operated upon.
	~LELFunctionDouble ()
	Destructor.
virtual void	eval (LELArray< Double > &result, const Slicer &section) const
	Recursively evaluate the expression.
virtual LELScalar< Double >	getScalar () const
	Recursively evaluate the scalar expression.
virtual Bool	prepareScalarExpr ()
	Do further preparations (e.g.
virtual String	className () const
	Get class name.
virtual Bool	lock (FileLocker::LockType, uInt nattempts)
	Handle locking/syncing of a lattice in a lattice expression.
virtual void	unlock ()
virtual Bool	hasLock (FileLocker::LockType) const
virtual void	resync ()
Private Member Functions
uInt	nMaskedElements (const LatticeExprNode &) const

uInt	nMaskedOn (const Array< Bool > &mask) const
Private Attributes
LELFunctionEnums::Function	function_p

Block< LatticeExprNode >	arg_p

Detailed Description

This LEL class handles numerical functions whose return type is a Double.

Intended use:

Internal

Review Status

Date Reviewed:: yyyy/mm/dd

Prerequisite

Etymology

This derived LEL letter class handles numerical functions (arbitrary number of arguments) which return a Double

Synopsis

This LEL letter class is derived from LELInterface. It is used to construct LEL objects that apply numerical functions of arbitrary number of arguments (but only 1 or 2 arguments currently implemented) to Lattice expressions. They operate on Double or DComplex Lattices and return a Double. The available C++ functions are min,max,pow,atan2,fmod,abs,arg,real,imag with equivalents in the enum of MIN,MAX,POW,ATAN2,FMOD,ABS,ARG,REAL, and IMAG.

There are also two other functions for which the input Lattice expression type must be a Bool. These are ntrue,nfalse with equivalents in the enum of NTRUE and NFALSE.

There is a further function for which the input Lattice expression type can be anything. This is nelements with equivalent in the enum of NELEM.

A description of the implementation details of the LEL classes can be found in Note 216

Example

Examples are not very useful as the user would never use these classes directly. Look in LatticeExprNode.cc to see how it invokes these classes. Examples of how the user would indirectly use this class (through the envelope) are:

    IPosition shape(2,5,10);
    ArrayLattice<Bool> v(shape); v.set(True);
    ArrayLattice<DComplex> w(shape); w.set(DComplex(2.0,3.0));
    ArrayLattice<Double> x(shape); x.set(0.05);
    ArrayLattice<Double> y(shape); y.set(2.0);
    ArrayLattice<Double> z(shape); y.set(2.0);
   
    z.copyData(min(x,y));                // z = min(x,y)
    z.copyData(imag(w));                 // z = imag(w)
    z.copyData(nelements(v));            // z = nelements(v)
    z.copyData(ntrue(v));                // z = ntrue(v)