describes any valid unit as a factor and a dimenion of SI units More...

#include <UnitVal.h>

Public Member Functions
	UnitVal ()
	Construct an non-dimensioned value of 1. More...

	UnitVal (const UnitVal &other)
	Copy constructor. More...

	UnitVal (Double factor)
	Construct an non-dimensioned value. More...

	UnitVal (Double factor, const String &s, UMaps *=0)
	Construct a fully dimensioned value. More...

	UnitVal (Double factor, Int pos)
	Construct a value with a single unit at position specified. More...

	~UnitVal ()
	Destructor. More...

UnitVal &	operator= (const UnitVal &other)
	Assignment (copy semantics) More...

UnitVal	pow (Int p)
	Raise a unit to an integer power. More...

UnitVal	root (Int p) const
	Take integer root. More...

UnitVal	sqrt () const


UnitVal &	operator*= (const UnitVal &other)
	Manipulate units. More...

UnitVal &	operator/= (const UnitVal &other)
	Divide different units. More...

Bool	operator== (const UnitVal &other) const
	Compare the dimensionality of different units. More...

Bool	operator!= (const UnitVal &other) const


const UnitDim &	getDim () const
	Get the data parts of the unit value definition. More...

Double	getFac () const
	Get the factor of the unit (as compared to pure SI units) More...

Static Public Member Functions
static Bool	check (const String &s)
	Convert a unit string to a proper unit value and cache the result. More...

static Bool	check (const String &s, UnitVal &loc)
	Convert a unit string to a proper unit value, cache the result and compare the dimension with the specified unit value. More...

Static Public Attributes

static UnitVal	NODIM
	Some constants to check type of units. More...

static UnitVal	UNDIM

static UnitVal	LENGTH

static UnitVal	MASS

static UnitVal	TIME

static UnitVal	CURRENT

static UnitVal	TEMPERATURE

static UnitVal	INTENSITY

static UnitVal	MOLAR

static UnitVal	ANGLE

static UnitVal	SOLIDANGLE

Protected Member Functions
void	init (Double factor)
	alternate initialization More...

void	init (Double factor, Int pos)

Static Private Member Functions
static Bool	create (const String &s, UnitVal &res, UMaps *=0)
	Convert (and check) a unit string to an SI value representation. More...

static Bool	create (MUString &str, UnitVal &res, UMaps *=0)

static Int	psign (MUString &str)
	Determine sign of unit power (i.e. More...

static Int	power (MUString &str)
	Determine exponent of unit symbol. More...

static Bool	field (MUString &str, UnitVal &res, UMaps *)
	Determine symbol name in unit string. More...

Private Attributes
Double	kindFactor
	The factor necessary to express the specified unit in the defining SI units. More...

UnitDim	kindDim
	The dimensions of the unit in the defining SI units. More...

Friends
class	UnitVal_static_initializer
	ensure that statics are initialized More...

UnitVal	operator* (const UnitVal &in, const UnitVal &other)
	Multiply. More...

UnitVal	operator/ (const UnitVal &in, const UnitVal &other)
	Divide. More...

ostream &	operator<< (ostream &os, const UnitVal &ku)
	Output a unit as a value and a string of SI defining units. More...

Detailed Description

describes any valid unit as a factor and a dimenion of SI units

Intended use:

Public interface

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: tUnit

Prerequisite

Unit

Etymology

The class name derives from Units and gives a Value for a unit string

Synopsis

Physical units are strings consisting of one or more names of known basic units, separated by '.' or ' ' (for multiplication) or '/' (for division). Each name can optionally be preceded by a standard decimal prefix, and/or followed by an (optionally signed) exponent. Example: km/s/(Mpc.s)2 is identical to km.s-1.Mpc-2.s-2

See the Unit class for more details.

The UnitVal class maps a Unit string to a factor and a dimension of SI defining units. E.g 'km/s' will be 1000 m.s-1. This class is only of interest if the manipulation of units is of direct interest. Normally units will be used as Quantities and Quantums (see the Quantum class) only, i.e. as a physical quantity having a value and unit. The class can also be used to check the validity of a unit string.

Constructing UnitVal values

UnitVal has the following constructors:

UnitVal() creates an (non-dimensioned) value 1.
UnitVal(Double f) creates an (non-dimensioned) value f.
UnitVal(Double f, String s) creates value f with unit s
UnitVal(Double f, Int i) (private) creates value f with unit at position i in dimension vector

Manipulating unit values

The UnitVal can be manipulated by the following operators and functions:

*, / generates combined UnitVal (e.g. 1 yd * 1 m = 0.9 m2)
pow(Int) UnitVal(2,"km")->pow(2) = 4000000 m2
root(Int) UnitVal(4000000,"m2")->root(2) = 2 km
==, != compares dimensions only: 1 yd == 5 ly: True
getFac() will return the factor (Double)
getDim() will return the dimensions (as UnitDim)
<< will output formatted unit (factor and dimension)

To aid in checking the dimensionality of units, the following constants are available:

Tip: Any other dimension can be checked by a combination; To check e;g; if a unit is an acceleration, use: UnitVal::LENGTH/UnitVal::TIME/UnitVal::TIME

Checking for valid unit strings

The validity of a unit string can be checked by:

// Check if the given String is a valid unit representation. The String
// will be cached in the unit maps for later reference if True
if (UnitVal::check("km/s/Mpc")) {...}

Example

An observation contains values in Janskys and in Westerbork Units. The data can be combined by the following code:

// The Fits tape gave JY, we check if defined, else we define them
if (!UnitVal::check("JY")) {
UnitMap::putUser("JY", UnitVal(1.,"Jy"), "FITS way to write Jy");
}
// The Fits tape gave WU (which are defined):
// We check if JY and WU are of the same dimension:
if (UnitVal(1.,"JY") != UnitVal(1.,"WU")) {
cerr << "Wrong dimension for either JY (" << 
UnitVal(1.,"JY")->getDim() <<
") or WU (" <<
UnitVal(1.,"WU")->getDim() << ")" << endl;
}
// And output the relation between WU and JY, and the WU value:
cout << "1 WU = " << (UnitVal(1.,"WU")/UnitVal(1.,"Jy"))->getVal() <<
" JY with 1 WU = " << UnitVal(1.,"WU") << endl;

Motivation

To separate the actual manipulation of unit values from the related quantity

To Do

Some inlining (did not work first go)

Definition at line 167 of file UnitVal.h.

Constructor & Destructor Documentation

casacore::UnitVal::UnitVal ( )

Construct an non-dimensioned value of 1.

casacore::UnitVal::UnitVal ( const UnitVal & other )

Copy constructor.

casacore::UnitVal::UnitVal ( Double factor )

inline

Construct an non-dimensioned value.

Definition at line 186 of file UnitVal.h.

References init().

casacore::UnitVal::UnitVal	(	Double	factor,
		const String &	s,
		UMaps *	= `0`
	)

Construct a fully dimensioned value.

Thrown Exceptions

AipsError

casacore::UnitVal::UnitVal	(	Double	factor,
		Int	pos
	)

inline

Construct a value with a single unit at position specified.

Definition at line 195 of file UnitVal.h.

References init().

casacore::UnitVal::~UnitVal ( )

Destructor.

Member Function Documentation

static Bool casacore::UnitVal::check ( const String & s )

static

Convert a unit string to a proper unit value and cache the result.

The function will return False if invalid string specified

static Bool casacore::UnitVal::check	(	const String &	s,
		UnitVal &	loc
	)

static

Convert a unit string to a proper unit value, cache the result and compare the dimension with the specified unit value.

False if any of the steps fails

static Bool casacore::UnitVal::create	(	const String &	s,
		UnitVal &	res,
		UMaps *	= `0`
	)

staticprivate

Convert (and check) a unit string to an SI value representation.

static Bool casacore::UnitVal::create	(	MUString &	str,
		UnitVal &	res,
		UMaps *	= `0`
	)

staticprivate

static Bool casacore::UnitVal::field	(	MUString &	str,
		UnitVal &	res,
		UMaps *
	)

staticprivate

Determine symbol name in unit string.

const UnitDim& casacore::UnitVal::getDim ( ) const

Get the data parts of the unit value definition.

Get the dimensions in the defining SI units

Double casacore::UnitVal::getFac ( ) const

Get the factor of the unit (as compared to pure SI units)

void casacore::UnitVal::init ( Double factor )

protected

alternate initialization

Referenced by UnitVal().

void casacore::UnitVal::init	(	Double	factor,
		Int	pos
	)

protected

Bool casacore::UnitVal::operator!= ( const UnitVal & other ) const

UnitVal& casacore::UnitVal::operator*= ( const UnitVal & other )

Manipulate units.

Multiply different units

UnitVal& casacore::UnitVal::operator/= ( const UnitVal & other )

Divide different units.

UnitVal& casacore::UnitVal::operator= ( const UnitVal & other )

Assignment (copy semantics)

Bool casacore::UnitVal::operator== ( const UnitVal & other ) const

Compare the dimensionality of different units.

UnitVal casacore::UnitVal::pow ( Int p )

Raise a unit to an integer power.

static Int casacore::UnitVal::power ( MUString & str )

staticprivate

Determine exponent of unit symbol.

static Int casacore::UnitVal::psign ( MUString & str )

staticprivate

Determine sign of unit power (i.e.

if '.' or '/')

UnitVal casacore::UnitVal::root ( Int p ) const

Take integer root.

Thrown Exceptions

AipsError if power equals zero
AipsError if unit dimensions not multiple of power

UnitVal casacore::UnitVal::sqrt ( ) const

Friends And Related Function Documentation

UnitVal operator*	(	const UnitVal &	in,
		const UnitVal &	other
	)

friend

Multiply.

UnitVal operator/	(	const UnitVal &	in,
		const UnitVal &	other
	)

friend

Divide.

ostream& operator<<	(	ostream &	os,
		const UnitVal &	ku
	)

friend

Output a unit as a value and a string of SI defining units.

friend class UnitVal_static_initializer

friend

ensure that statics are initialized

Definition at line 176 of file UnitVal.h.

Member Data Documentation

UnitVal casacore::UnitVal::ANGLE

static

Definition at line 264 of file UnitVal.h.

UnitVal casacore::UnitVal::CURRENT

static

Definition at line 260 of file UnitVal.h.

UnitVal casacore::UnitVal::INTENSITY

static

Definition at line 262 of file UnitVal.h.

UnitDim casacore::UnitVal::kindDim

private

The dimensions of the unit in the defining SI units.

Definition at line 278 of file UnitVal.h.

Double casacore::UnitVal::kindFactor

private

The factor necessary to express the specified unit in the defining SI units.

Definition at line 275 of file UnitVal.h.

UnitVal casacore::UnitVal::LENGTH

static

Definition at line 257 of file UnitVal.h.

UnitVal casacore::UnitVal::MASS

static

Definition at line 258 of file UnitVal.h.

UnitVal casacore::UnitVal::MOLAR

static

Definition at line 263 of file UnitVal.h.

UnitVal casacore::UnitVal::NODIM

static

Some constants to check type of units.

Definition at line 255 of file UnitVal.h.

UnitVal casacore::UnitVal::SOLIDANGLE

static

Definition at line 265 of file UnitVal.h.

UnitVal casacore::UnitVal::TEMPERATURE

static

Definition at line 261 of file UnitVal.h.

UnitVal casacore::UnitVal::TIME

static

Definition at line 259 of file UnitVal.h.

UnitVal casacore::UnitVal::UNDIM

static

Definition at line 256 of file UnitVal.h.

The documentation for this class was generated from the following file:

casa/Quanta/UnitVal.h

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Static Private Member Functions

Private Attributes

Friends

Detailed Description

Intended use:

Review Status

Prerequisite

Etymology

Synopsis

Constructing UnitVal values

Manipulating unit values

Checking for valid unit strings

Example

Motivation

To Do

Constructor & Destructor Documentation

Thrown Exceptions

Member Function Documentation

Thrown Exceptions

Friends And Related Function Documentation

Member Data Documentation