gwy_shape_fit_preset_needs_same_units ()

gboolean
gwy_shape_fit_preset_needs_same_units (GwyShapeFitPreset *preset);

Reports if a 3D geometrical shape fitter preset requires the same lateral and value units.

For instance, fitting a sphere is meaningless if the horizontal and vertical radii would be different physical quantities.

Since: 2.47

gwy_shape_fit_preset_get_nparams ()

guint
gwy_shape_fit_preset_get_nparams (GwyShapeFitPreset *preset);

Reports the number of parameters of a 3D geometrical shape fitter preset.

Since: 2.47

gwy_shape_fit_preset_get_param_name ()

const gchar *
gwy_shape_fit_preset_get_param_name (GwyShapeFitPreset *preset,
                                     guint i);

Gets the name of a fitting parameter of a 3D geometrical shape fitter preset.

The name may contain Pango markup.

Since: 2.47

gwy_shape_fit_preset_get_param_description ()

const gchar *
gwy_shape_fit_preset_get_param_description
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the description of a fitting parameter of a 3D geometrical shape fitter preset.

The description may contain Pango markup. It may also be NULL if the parameter is currently undescribed.

Since: 2.61

gwy_shape_fit_preset_get_param_flags ()

GwyNLFitParamFlags
gwy_shape_fit_preset_get_param_flags (GwyShapeFitPreset *preset,
                                      guint i);

Gets the properties of a fitting parameter of a 3D geometrical shape fitter preset.

Since: 2.47

gwy_shape_fit_preset_get_param_units ()

GwySIUnit *
gwy_shape_fit_preset_get_param_units (GwyShapeFitPreset *preset,
                                      guint i,
                                      GwySIUnit *siunit_xy,
                                      GwySIUnit *siunit_z);

Derives the SI unit of a fitting parameter from the units of abscissa and ordinate.

Note that angle parameters are by default in radians and thus unitless. If you want to convert them to degrees for presentation to the user you must do it explicitly.

Since: 2.47

gwy_shape_fit_preset_get_param_power_xy ()

gint
gwy_shape_fit_preset_get_param_power_xy
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the power of abscissa units in a shape fitting parameter.

Usually it is easier to let gwy_shape_fit_preset_get_param_units() derive the parameter units.

Since: 2.50

gwy_shape_fit_preset_get_param_power_z ()

gint
gwy_shape_fit_preset_get_param_power_z
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the power of ordinate units in a shape fitting parameter.

Usually it is easier to let gwy_shape_fit_preset_get_param_units() derive the parameter units.

Since: 2.50

gwy_shape_fit_preset_get_nsecondary ()

guint
gwy_shape_fit_preset_get_nsecondary (GwyShapeFitPreset *preset);

Reports the number of secondary (derived) quantities of a 3D geometrical shape fitter preset.

Since: 2.47

gwy_shape_fit_preset_get_secondary_name ()

const gchar *
gwy_shape_fit_preset_get_secondary_name
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the name of a secondary (derived) quantity of a 3D geometrical shape fitter preset.

The name may contain Pango markup.

Since: 2.47

gwy_shape_fit_preset_get_secondary_description ()

const gchar *
gwy_shape_fit_preset_get_secondary_description
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the description of a secondary quantity of a 3D geometrical shape fitter preset.

The description may contain Pango markup. It may also be NULL if the quantity is currently undescribed.

Since: 2.61

gwy_shape_fit_preset_get_secondary_flags ()

GwyNLFitParamFlags
gwy_shape_fit_preset_get_secondary_flags
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the properties of a secondary (derived) quantity of a 3D geometrical shape fitter preset.

Since: 2.47

gwy_shape_fit_preset_get_secondary_value ()

gdouble
gwy_shape_fit_preset_get_secondary_value
                               (GwyShapeFitPreset *preset,
                                guint i,
                                const gdouble *param);

Calculates the value of a secondary (derived) quantity of a 3D geometrical shape fitter preset.

Since: 2.47

gwy_shape_fit_preset_get_secondary_error ()

gdouble
gwy_shape_fit_preset_get_secondary_error
                               (GwyShapeFitPreset *preset,
                                guint i,
                                const gdouble *param,
                                const gdouble *error,
                                const gdouble *correl);

Calculates the error of a secondary (derived) quantity of a 3D geometrical shape fitter preset.

The error is calculated by numerical differentiation of the function and applying the law of error propagation.

Since: 2.47

gwy_shape_fit_preset_get_secondary_units ()

GwySIUnit *
gwy_shape_fit_preset_get_secondary_units
                               (GwyShapeFitPreset *preset,
                                guint i,
                                GwySIUnit *siunit_xy,
                                GwySIUnit *siunit_z);

Derives the SI unit of a secondary (derived) quantity from the units of abscissa and ordinate.

Note that angle parameters are by default in radians and thus unitless. If you want to convert them to degrees for presentation to the user you must do it explicitly.

Since: 2.47

gwy_shape_fit_preset_get_secondary_power_xy ()

gint
gwy_shape_fit_preset_get_secondary_power_xy
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the power of abscissa units in a shape fitting secondary (derived) quantity.

Usually it is easier to let gwy_shape_fit_preset_get_secondary_units() derive the quantity units.

Since: 2.50

gwy_shape_fit_preset_get_secondary_power_z ()

gint
gwy_shape_fit_preset_get_secondary_power_z
                               (GwyShapeFitPreset *preset,
                                guint i);

Gets the power of ordinate units in a shape fitting secondary (derived) quantity.

Usually it is easier to let gwy_shape_fit_preset_get_secondary_units() derive the quantity units.

Since: 2.50

gwy_shape_fit_preset_setup ()

void
gwy_shape_fit_preset_setup (GwyShapeFitPreset *preset,
                            const GwyXYZ *points,
                            guint n,
                            gdouble *params);

Initialises parameter values of a 3D geometrical shape fitter preset.

The parameters are quickly set to reasonable values that roughly correspond to the ranges of the data points. They may serve as starting values for manual experimentation but often will not be good enough as initial parameter estimates for the fit. See also gwy_shape_fit_preset_guess().

Since: 2.47

gwy_shape_fit_preset_guess ()

gboolean
gwy_shape_fit_preset_guess (GwyShapeFitPreset *preset,
                            const GwyXYZ *points,
                            guint n,
                            gdouble *params);

Estimates parameter values of a 3D geometrical shape fitter preset.

This function tries to find initial parameter estimates that are good enough for the fit the converge. Of course, it is not guaranteed it always succeeds. For some shapes it can be noticeably slower than gwy_shape_fit_preset_setup().

The estimate may not be deterministic. For large point sets some estimates are carried out using a randomly selected subset of points.

If the function cannot find how the data points could correspond to the preset geometrical shape it return FALSE. Parameter values are still set. However, in this case they may be no better than from gwy_shape_fit_preset_setup().

Since: 2.47

gwy_shape_fit_preset_get_value ()

gdouble
gwy_shape_fit_preset_get_value (GwyShapeFitPreset *preset,
                                gdouble x,
                                gdouble y,
                                const gdouble *params);

Calculates the value of a 3D geometrical shape fitter preset in a single point.

If you want multiple values you should use either gwy_shape_fit_preset_calculate_z() or gwy_shape_fit_preset_calculate_xyz() instead of calling this function in a cycle.

Since: 2.47

gwy_shape_fit_preset_calculate_z ()

void
gwy_shape_fit_preset_calculate_z (GwyShapeFitPreset *preset,
                                  const GwyXYZ *points,
                                  gdouble *z,
                                  guint n,
                                  const gdouble *params);

Calculates values of a 3D geometrical shape fitter preset in an array of points.

The z-coordinates in points are ignored. Only the lateral coordinates are used.

See also gwy_shape_fit_preset_calculate_xyz().

Since: 2.47

gwy_shape_fit_preset_calculate_xyz ()

void
gwy_shape_fit_preset_calculate_xyz (GwyShapeFitPreset *preset,
                                    GwyXYZ *points,
                                    guint n,
                                    const gdouble *params);

Calculates values of a 3D geometrical shape fitter preset in an array of points.

See also gwy_shape_fit_preset_calculate_z().

Since: 2.47

gwy_shape_fit_preset_create_fitter ()

GwyNLFitter *
gwy_shape_fit_preset_create_fitter (GwyShapeFitPreset *preset);

Creates a non-linear least-squares fitter for a 3D geometrical shape.

The created fitter will be of the opaque indexed data type, as created with gwy_math_nlfit_new_idx().

If you do not need to modify the fitter settings you can use gwy_shape_fit_preset_fit() directly with NULL fitter.

Since: 2.47

gwy_shape_fit_preset_fit ()

GwyNLFitter *
gwy_shape_fit_preset_fit (GwyShapeFitPreset *preset,
                          GwyNLFitter *fitter,
                          const GwyXYZ *points,
                          guint n,
                          gdouble *params,
                          const gboolean *fixed_param,
                          gdouble *rss);

Performs a non-linear least-squares fit with a 3D geometrical shape fitter.

If you pass NULL fitter the function creates one for you and immediately performs the fit. If you want to modify the fitter settings beforehand or set callback functions create it using gwy_shape_fit_preset_create_fitter() and pass to this function. The fitter must be created for the same preset.

Additional quantities such as parameter errors or the correlation matrix can be obtained from the fitter. See gwy_math_nlfit_fit_full() for details.

Since: 2.47

gwy_shape_fit_preset_quick_fit ()

GwyNLFitter *
gwy_shape_fit_preset_quick_fit (GwyShapeFitPreset *preset,
                                GwyNLFitter *fitter,
                                const GwyXYZ *points,
                                guint n,
                                gdouble *params,
                                const gboolean *fixed_param,
                                gdouble *rss);

Performs a rough non-linear least-squares fit with a 3D geometrical shape fitter.

See gwy_shape_fit_preset_fit() for discussion. This functions differs by using a reduced number of points to perform the fit (unless the input set is small) and may also set fitter parameters to make the least squares method terminate faster. The input points are reduced the same way as in gwy_surface_reduce_points().

Since: 2.48

gwy_shape_fit_presets ()

GwyInventory *
gwy_shape_fit_presets (void);

Gets inventory with all the 3D geometric shape fitting presets.

Since: 2.47

struct GwyShapeFitPreset

struct GwyShapeFitPreset;

struct GwyShapeFitPresetClass

struct GwyShapeFitPresetClass {
    GwyResourceClass parent_class;
};