GwySIUnit

GwySIUnit — SI unit representation, physical quantitiy formatting

Synopsis

#include <libgwyddion/gwyddion.h>

struct              GwySIUnit;
struct              GwySIUnitClass;
                    GwySIValueFormat;
#define             gwy_si_unit_duplicate               (siunit)
GwySIUnit *         gwy_si_unit_new                     (const gchar *unit_string);
GwySIUnit *         gwy_si_unit_new_parse               (const gchar *unit_string,
                                                         gint *power10);
void                gwy_si_unit_set_from_string         (GwySIUnit *siunit,
                                                         const gchar *unit_string);
void                gwy_si_unit_set_from_string_parse   (GwySIUnit *siunit,
                                                         const gchar *unit_string,
                                                         gint *power10);
gchar *             gwy_si_unit_get_string              (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style);
GwySIUnit *         gwy_si_unit_multiply                (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2,
                                                         GwySIUnit *result);
GwySIUnit *         gwy_si_unit_divide                  (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2,
                                                         GwySIUnit *result);
GwySIUnit *         gwy_si_unit_power                   (GwySIUnit *siunit,
                                                         gint power,
                                                         GwySIUnit *result);
GwySIUnit *         gwy_si_unit_nth_root                (GwySIUnit *siunit,
                                                         gint ipower,
                                                         GwySIUnit *result);
GwySIUnit *         gwy_si_unit_power_multiply          (GwySIUnit *siunit1,
                                                         gint power1,
                                                         GwySIUnit *siunit2,
                                                         gint power2,
                                                         GwySIUnit *result);
gboolean            gwy_si_unit_equal                   (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2);
GwySIValueFormat *  gwy_si_unit_get_format              (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble value,
                                                         GwySIValueFormat *format);
GwySIValueFormat *  gwy_si_unit_get_format_for_power10  (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gint power10,
                                                         GwySIValueFormat *format);
GwySIValueFormat *  gwy_si_unit_get_format_with_resolution
                                                        (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble maximum,
                                                         gdouble resolution,
                                                         GwySIValueFormat *format);
GwySIValueFormat *  gwy_si_unit_get_format_with_digits  (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble maximum,
                                                         gint sdigits,
                                                         GwySIValueFormat *format);
void                gwy_si_unit_value_format_free       (GwySIValueFormat *format);
void                gwy_si_unit_value_format_set_units  (GwySIValueFormat *format,
                                                         const gchar *units);

Object Hierarchy

  GObject
   +----GwySIUnit

Implemented Interfaces

GwySIUnit implements GwySerializable.

Signals

  "value-changed"                                  : Run First

Description

GwySIUnit object represents a physical SI unit (or any other unit), it can be created from a unit string with gwy_si_unit_new().

GwySIUnit is also responsible for prefixes selection and generally formatting of physical quantities (see also gwymath for pure number formatting functions). There are several functions computing value format (as a GwySIValueFormat structure) with given resolution -- gwy_si_unit_get_format_with_resolution(), or number of significant digits -- gwy_si_unit_get_format_with_digits().

Details

struct GwySIUnit

struct GwySIUnit;

The GwySIUnit struct contains private data only and should be accessed using the functions below.


struct GwySIUnitClass

struct GwySIUnitClass {
    GObjectClass parent_class;

    void (*value_changed)(GwySIUnit *siunit);

    void (*reserved1)(void);
    void (*reserved2)(void);
};


GwySIValueFormat

typedef struct {
    gdouble magnitude;
    gint precision;
    gchar *units;
    GString *units_gstring;
} GwySIValueFormat;

A physical quantity formatting information.

The magnitude and precision fields can be directly modified if necessary. Units must be always set with gwy_si_unit_value_format_set_units() to update the internal representation properly.

gdouble magnitude;

Number to divide a quantity by (a power of 1000).

gint precision;

Number of decimal places to format a quantity to.

gchar *units;

Units to put after quantity divided by magnitude. This is actually an alias to units_gstring->str.

GString *units_gstring;

GString used to represent units internally.

gwy_si_unit_duplicate()

#define             gwy_si_unit_duplicate(siunit)

Convenience macro doing gwy_serializable_duplicate() with all the necessary typecasting.

siunit :

An SI unit to duplicate.

gwy_si_unit_new ()

GwySIUnit *         gwy_si_unit_new                     (const gchar *unit_string);

Creates a new SI unit from string representation.

Unit string represents unit with no prefixes (e. g. "m", "N", "A", etc.)

unit_string :

Unit string (it can be NULL for an empty unit).

Returns :

A new SI unit.

gwy_si_unit_new_parse ()

GwySIUnit *         gwy_si_unit_new_parse               (const gchar *unit_string,
                                                         gint *power10);

Creates a new SI unit from string representation.

This is a more powerful version of gwy_si_unit_new(): unit_string may be a relatively complex unit, with prefixes, like "pA/s" or "km^2". Beside conversion to a base SI unit like "A/s" or "m^2" it also computes the power of 10 one has to multiply the base unit with to get an equivalent of unit_string.

For example, for "pA/s" it will store -12 to power10 because 1 pA/s is 1e-12 A/s, for "km^2" it will store 6 to power10 because 1 km^2 is 1e6 m^2.

unit_string :

Unit string (it can be NULL for an empty unit).

power10 :

Where power of 10 should be stored (or NULL).

Returns :

A new SI unit.

gwy_si_unit_set_from_string ()

void                gwy_si_unit_set_from_string         (GwySIUnit *siunit,
                                                         const gchar *unit_string);

Sets string that represents unit.

It must be base unit with no prefixes (e. g. "m", "N", "A", etc.).

siunit :

An SI unit.

unit_string :

Unit string to set siunit from (it can be NULL for an empty unit).

gwy_si_unit_set_from_string_parse ()

void                gwy_si_unit_set_from_string_parse   (GwySIUnit *siunit,
                                                         const gchar *unit_string,
                                                         gint *power10);

Changes an SI unit according to string representation.

This is a more powerful version of gwy_si_unit_set_from_string(), please see gwy_si_unit_new_parse() for some discussion.

siunit :

An SI unit.

unit_string :

Unit string to set siunit from (it can be NULL for an empty unit).

power10 :

Where power of 10 should be stored (or NULL).

gwy_si_unit_get_string ()

gchar *             gwy_si_unit_get_string              (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style);

Obtains string representing a SI unit.

siunit :

An SI unit.

style :

Unit format style.

Returns :

A newly allocated string that represents the base unit (with no prefixes).

gwy_si_unit_multiply ()

GwySIUnit *         gwy_si_unit_multiply                (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2,
                                                         GwySIUnit *result);

Multiplies two SI units.

siunit1 :

An SI unit.

siunit2 :

An SI unit.

result :

An SI unit to set to product of siunit1 and siunit2. It is safe to pass one of siunit1, siunit2. It can be NULL too, a new SI unit is created then and returned.

Returns :

When result is NULL, a newly created SI unit that has to be dereferenced when no longer used later. Otherwise result itself is simply returned, its reference count is NOT increased.

gwy_si_unit_divide ()

GwySIUnit *         gwy_si_unit_divide                  (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2,
                                                         GwySIUnit *result);

Divides two SI units.

siunit1 :

An SI unit.

siunit2 :

An SI unit.

result :

An SI unit to set to quotient of siunit1 and siunit2. It is safe to pass one of siunit1, siunit2. It can be NULL too, a new SI unit is created then and returned.

Returns :

When result is NULL, a newly created SI unit that has to be dereferenced when no longer used later. Otherwise result itself is simply returned, its reference count is NOT increased.

gwy_si_unit_power ()

GwySIUnit *         gwy_si_unit_power                   (GwySIUnit *siunit,
                                                         gint power,
                                                         GwySIUnit *result);

Computes a power of an SI unit.

siunit :

An SI unit.

power :

Power to raise siunit to.

result :

An SI unit to set to power of siunit. It is safe to pass siunit itself. It can be NULL too, a new SI unit is created then and returned.

Returns :

When result is NULL, a newly created SI unit that has to be dereferenced when no longer used later. Otherwise result itself is simply returned, its reference count is NOT increased.

gwy_si_unit_nth_root ()

GwySIUnit *         gwy_si_unit_nth_root                (GwySIUnit *siunit,
                                                         gint ipower,
                                                         GwySIUnit *result);

Calulates n-th root of an SI unit.

This operation fails if the result would have fractional powers that are not representable by GwySIUnit.

siunit :

An SI unit.

ipower :

The root to take: 2 means a quadratic root, 3 means cubic root, etc.

result :

An SI unit to set to power of siunit. It is safe to pass siunit itself. It can be NULL too, a new SI unit is created then and returned.

Returns :

On success: When result is NULL, a newly created SI unit that has to be dereferenced when no longer used later, otherwise result itself is simply returned, its reference count is NOT increased. On failure NULL is always returned.

Since 2.5


gwy_si_unit_power_multiply ()

GwySIUnit *         gwy_si_unit_power_multiply          (GwySIUnit *siunit1,
                                                         gint power1,
                                                         GwySIUnit *siunit2,
                                                         gint power2,
                                                         GwySIUnit *result);

Computes the product of two SI units raised to arbitrary powers.

This is the most complex SI unit arithmetic function. It can be easily chained when more than two units are to be multiplied.

siunit1 :

An SI unit.

power1 :

Power to raise siunit1 to.

siunit2 :

An SI unit.

power2 :

Power to raise siunit2 to.

result :

An SI unit to set to siunit1^power1*siunit2^power2. It is safe to pass siunit1 or siunit2. It can be NULL too, a new SI unit is created then and returned.

Returns :

When result is NULL, a newly created SI unit that has to be dereferenced when no longer used later. Otherwise result itself is simply returned, its reference count is NOT increased.

Since 2.4


gwy_si_unit_equal ()

gboolean            gwy_si_unit_equal                   (GwySIUnit *siunit1,
                                                         GwySIUnit *siunit2);

Checks whether two SI units are equal.

siunit1 :

First unit.

siunit2 :

Second unit.

Returns :

TRUE if units are equal.

gwy_si_unit_get_format ()

GwySIValueFormat *  gwy_si_unit_get_format              (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble value,
                                                         GwySIValueFormat *format);

Finds a good format for representing a value.

The values should be then printed as value/format->magnitude [format->units] with format->precision decimal places.

siunit :

An SI unit.

style :

Unit format style.

value :

Value the format should be suitable for.

format :

A value format to set-up, may be NULL, a new value format is allocated then.

Returns :

The value format. If format was NULL, a newly allocated format is returned, otherwise (modified) format itself is returned.

gwy_si_unit_get_format_for_power10 ()

GwySIValueFormat *  gwy_si_unit_get_format_for_power10  (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gint power10,
                                                         GwySIValueFormat *format);

returns it. format: A value format to set-up, may be NULL, a new value format is allocated then.

Finds format for representing a specific power-of-10 multiple of a unit.

The values should be then printed as value/format->magnitude [format->units] with format->precision decimal places.

This function does not change the precision field of format.

siunit :

An SI unit.

style :

Unit format style.

power10 :

Power of 10, in the same sense as gwy_si_unit_new_parse()

Returns :

The value format. If format was NULL, a newly allocated format is returned, otherwise (modified) format itself is returned.

gwy_si_unit_get_format_with_resolution ()

GwySIValueFormat *  gwy_si_unit_get_format_with_resolution
                                                        (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble maximum,
                                                         gdouble resolution,
                                                         GwySIValueFormat *format);

Finds a good format for representing a range of values with given resolution.

The values should be then printed as value/format->magnitude [format->units] with format->precision decimal places.

siunit :

A SI unit.

style :

Unit format style.

maximum :

The maximum value to be represented.

resolution :

The smallest step (approximately) that should make a visible difference in the representation.

format :

A value format to set-up, may be NULL, a new value format is allocated then.

Returns :

The value format. If format was NULL, a newly allocated format is returned, otherwise (modified) format itself is returned.

gwy_si_unit_get_format_with_digits ()

GwySIValueFormat *  gwy_si_unit_get_format_with_digits  (GwySIUnit *siunit,
                                                         GwySIUnitFormatStyle style,
                                                         gdouble maximum,
                                                         gint sdigits,
                                                         GwySIValueFormat *format);

Finds a good format for representing a values with given number of significant digits.

The values should be then printed as value/format->magnitude [format->units] with format->precision decimal places.

siunit :

A SI unit.

style :

Unit format style.

maximum :

The maximum value to be represented.

sdigits :

The number of significant digits the value should have.

format :

A value format to set-up, may be NULL, a new value format is allocated then.

Returns :

The value format. If format was NULL, a newly allocated format is returned, otherwise (modified) format itself is returned.

gwy_si_unit_value_format_free ()

void                gwy_si_unit_value_format_free       (GwySIValueFormat *format);

Frees a value format structure.

format :

A value format to free.

gwy_si_unit_value_format_set_units ()

void                gwy_si_unit_value_format_set_units  (GwySIValueFormat *format,
                                                         const gchar *units);

Sets the units field of a value format structure.

This function keeps the units and units_gstring fields consistent.

format :

A value format to set units of.

units :

The units string.

Signal Details

The "value-changed" signal

void                user_function                      (GwySIUnit *gwysiunit,
                                                        gpointer   user_data)      : Run First

The ::value-changed signal is emitted whenever SI unit changes.

gwysiunit :

The GwySIUnit which received the signal.

user_data :

user data set when the signal handler was connected.