footprint class

footprint

The footprint class is a descendant of the direction_cosine class., which defines the point on a unit spare with a timestamp and uncertainty.

Constructors

footprint(const double l, const double m, const double n)

Create a footprint with a direction cosine of (l, m, n). The current system time is registered as a timestamp. A default uncertainty value, 1.0 arcsecond, is adopted.

l

l-coordinate

m

m-coordinate

n

n-coordinate

footprint(const double x, const double y, const double z, const timestamp_t& t, const angle& s = arcsec(1.0))

Create a footprint with a direction cosine of (l, m, n, t, s), where t is the timestamp and s is the uncertainty. The uncertainty can be skipped. If skipped, a default uncertainty value, 1.0 arcsecond, is adopted.

l

l-coordinate

m

m-coordinate

n

n-coordinate

t

the timestamp.

s

the uncertainty.

footprint(const longitude& lon, const latitude& lat, const timestamp_t& t, const angle& s = arcsec(1.0))

Create a footprint with a direction cosine, timestamp, and uncertainty. The direction cosine is defined by (lon, lat), where lon is the longitude and lat is the latitude. The uncertainty can be skipped. If skipped, a default uncertainty value, 1. arcsecond is adopted.

lon

the longitude angle.

lat

the latitude angle.

t

the timestamp.

s

the uncertainty.

Functions

const double
inner_product(const vector3& v) const

Calculate an inner product with another vector3 instance v. Inherited from the direction_cosine class.

v

a vector3 instance.

const vector3
outer_product(const vector3& v) const

Calculate an outer product with another vectore instance v. Inherited from the direction_cosine class.

v

a vector3 instance.

const double
separation_cosine(const vector3& v) const

Calculate cosθ, where θ is the separation angle between another vector3 instance v. Inherited from the direction_cosine class.

v

a vector3 instance.

const angle
separation(const vector3& v) const

Calculate θ, where θ is the separation angle between another vector3 instance v. Inherited from the direction_cosine class.

v

a vector3 instance.

const direction_cosine
get_pole(const vector3& v) const

Calculate the pole direction perpendicular to both this instance and a vector3 instance. Inherited from the direction_cosine class.

v

a vector3 instance.

const direction_cosine
pivot(const direction_cosine& q, const angle& f1, const angle& f2) const

Obtain the direction which is separated by f1 from this instance and separated by f2 from another direction_cosine q. Inherited from the direction_cosine class.

q

an anchor point.

f1

the separation angle from this instance.

f2

the separation angle from the anchor point q.

const footprint
extend_to(const footprint& q, const angle& d) const

Obtain an extended footprint point toward q. The separation angle from this instance is specified by d. Override the function inherited from the direction_cosine class.

q

a footprint instance, which defines the direction to extend.

d

a separation angle between this instance and the extended point.

const footprint
extend_to(const footprint& q, const double f) const

Obtain an extended footprint point toward q. The separation from this instance is specified by f, a separation normalized by the distance between this instance and q. Override the function inherited from the direction_cosine class.

q

a footprint instance, which defines the direction to extend.

f

a separation factor.

const bool
neighbor_to(const vector3& v, const angle& range) const

Return true if the vector3 instance is located within range.

v

a vector3 instance. Internally converted into direction_cosine.

range

a search radius angle.

const bool
neighbor_to(const vector3& v) const

Return true if the vector3 instance is located within the uncertainty of this instance.

v

a vector3 instance. Internally converted into direction_cosine.

const bool
neighbor_to(const footprint& p) const

Return true if the footprint instance is located within the uncertainty. The uncertainties of both instances are taken into account.

p

a footprint instance.

const bool
match(const footprint& p, const angle& range, const sec_t& trange) const

Return true if the footprint p is considered as identical to this instance. The search radius is specified by range, while the search time window is given by trange.

p

a footprint instance.

range

a search radius.

void
print() const

Write down the (l,m,n) coordinate in stdout as well as the uncertainty in arcsecond and the timestamp in the ISO format.

Attributes

l

(double) l-element of the direction cosine. Inherited from direction_cosine.

m

(double) m-element of the direction cosine. Inherited from direction_cosine.

n

(double) n-element of the direction cosine. Inherited from direction_cosine.

t

(timestamp_t) the timestamp of the direction cosine.

lon

(longitude) the longitude angle of the direction cosine. Inherited from direction_cosine.

lat

(latitude) the latitude angle of the direction cosine. Inherited from direction_cosine.

x

(double) the reference to the l-element of the direction cosine. Inherited from direction_cosine.

y

(double) the reference to the m-element of the direction cosine. Inherited from direction_cosine.

z

(double) the reference to the n-element of the direction cosine. Inherited from direction_cosine.

d

(double) always unity. Inherited from direction_cosine.