European Space Agency

Royal Belgian Institute for Aeronomy

uf421 - initialize and close a field line segment

subroutine  uf421(kiniclo, mgeo, pb, palt, plen, jind, ifail)

Parameters:

• kiniclo [integer4,in] :: Flag to selection initialisation or closing (1 or 2, respectively)

• mgeo [zgeo,in/out] :: Geographic location of the start or end point

• pb [real8,out] :: Magnetic field intensity at mgeo.

• palt [real8,out] :: Altitude of mgeo.

• plen [real8,out] :: Arc length of the field line segment

• jind [integer4,out] :: Index in the common block uc170.

• ifail [integer4,out] :: error flag (see Diagnostics)

Description

When the argument kiniclo is equal to 1, the subroutine uf421() initializes the common block uc170 to store a magnetic field line segment which starts at mgeo. As result, the arguments pb and palt are set to the magnetic field intensity and altitude of mgeo. The arguments plen and jind are set to 0.0 and 1, respectively.

When the argument kiniclo is equal to 2, the subroutine uf421() closes the magnetic field line segment stored in the common block uc170. As result, the arguments mgeo, pb and palt are set to the geographic location of the last point, its magnetic field intensity and altitude, respectively. The total arc length of the field line segment and the total number of points stored in the common block are returned by the arguments plen and jind, respectively.

Diagnostics

• -42101, not used

• -42102, the size of the common block UC170 has been overrun

• -42103, problem with the field line description

Common Blocks

• uc160 - general constants

• uc170 - temporary magnetic field line

• uc190 - control parameters, set 1

Dependencies

Called by

• uf420 - trace a magnetic field line segment passing through a given position

Calls

• um530 - evaluate the magnetic field vector

• ut999 - radius of curvature in a dipolar magnetic field

See also

None

Reported Bugs

None

Examples

None

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UNILIB/tags/v3.03