Gaussian1DParam.h

The width of the Gaussian (for the constructors or the setWidth function) is always specified in terms of the full width at half maximum (FWHM). It is always positive and attempts to set a non-positive width will throw an assertion when in debug mode.

The peak height of the Gaussian can be specified at construction time or by using the setHeight function. Alternatively the setFlux function can be used to implicitly set the peak height by specifying the integrated area under the Gaussian. The height (or flux) can be positive, negative or zero, as this class makes no assumptions on what quantity the height represents.

Changing the width of the Gaussian will not affect its peak height but will change its flux. So you should always set the width before setting the flux.

The parameter interface (see FunctionParam class), is used to provide an interface to the Fitting classes.

There are 3 parameters that are used to describe the Gaussian:

The height of the Gaussian. This is identical to the value returned using the height() member function.
The center of the Gaussian in the x direction. This is identical to the value returned using the center() member function.
The width (FWHM) of the Gaussian. To aid convergence of the non-linear fitting routines this parameter is allowed to be negative. This does not affect the shape of the Gaussian as the square of the width is used when evaluating the function.

An enumeration for the HEIGHT, WIDTH and CENTER parameter index is provided, enabling the setting and reading of parameters with the [] operator. The mask() methods can be used to check and set the parameter masks.

This class is in general used implicitly by the Gaussian1D class only.

Example

    Gaussian1D<Double> gf(5.0, 25.0, 7);
    gf(25);            // = 5.0
    gf.setHeight(1.0);
    gf[WIDTH](2.0);                
    gf[CENTER](0.0);
    gf(1);             // = 0.5*height = 0.5

Template Type Argument Requirements (T)

T should have standard numerical operators and exp() function. Current implementation only tested for real types (and their AutoDiffs).

Thrown Exceptions

Assertion in debug mode if attempt is made to set a negative width
AipsError if incorrect parameter number specified.

To Do

Gaussians that know about their DFT's could be required eventually.

Member Description

enum

Gaussian1DParam()
explicit Gaussian1DParam(const T &height)
Gaussian1DParam(const T &height, const T &center)
Gaussian1DParam(const T &height, const T &center, const T &width)

Constructs the one dimensional Gaussians. Defaults: height=1, center=0, width(FWHM)=1.

Could not use default arguments that worked both with gcc and IRIX and all templates

Gaussian1DParam(const Gaussian1DParam<T> &other)
template <class W> Gaussian1DParam(const Gaussian1DParam<W> &other) : Function1D<T>(other), fwhm2int(T(1.0)/sqrt(log(T(16.0))))

Copy constructor (deep copy)

Gaussian1DParam<T> &operator=(const Gaussian1DParam<T> &other)

Copy assignment (deep copy)

virtual ~Gaussian1DParam()

Destructor

virtual const String &name() const

Give name of function

T height() const
void setHeight(const T &height)

Get or set the peak height of the Gaussian

T flux() const
void setFlux(const T &flux)

Get or set the analytical integrated area underneath the Gaussian. Use these functions as an alternative to the height functions.

T center() const
void setCenter(const T &cnter)

Get or set the center ordinate of the Gaussian

T width() const
void setWidth(const T &width)

Get or set the FWHM of the Gaussian.