IGRF Calculation
GIGRF, SDGRF, SPGRF, SIGRF, TYEAR, IGRFC, IGRFM
NAME
gigrf - Select IGRF model by generation number and specify time epoch
sdgrf / spgrf / sigrf - Select DGRF / PGRF / Tentative IGRF model
and specify time epoch
tyear - Change only time epoch of calculation, without changing the IGRF
model and its reference year as already selected
igrfc - Specify position and get total force IGRF value
igrfm - Get full components of IGRF vector
SYNOPSIS
call gigrf(ngen, year)
call sdgrf(year)
call spgrf(year)
call sigrf(year)
call tyear(year)
year [float] Time epoch (in year) of calculation
ngen [int] Generation number of IGRF model
call igrfc(fi, fk, h, f)
fi, fk [float] Lat. and Lon. (in degrees) of the point of calculation
h [float] Altitude (in m) of the point of calculation
f [float] Calculated results.
Total force (in nT) value of the model is given.
call igrfm(fm)
fm [float] Array in which vector values (6 elements) of the model are
given. 3 orthogonal components North(X) / East(Y) / Downward
(Z) (in nT), and Horizontal(H) component (in nT),
Inclination (in degrees) and Declination (in degrees) are
put into the array in sequence.
USAGE
First specify the ModelGeneration (IGRF-n) or ModelType (IGRF/DGRF/PGRF)
with the Year of Calc. by `call gigrf(ngen, year)`,
`call sigrf(year)`, `call spgrf(year)`, or `call sdgrf(year)`.
Then, `call igrfc(FI, FK, H, F)` gives TotalForce (F) of that model
at the point of Lat.=FI, Long.=FK, Alt.=H
If other components are desired, `call igrfm(FM)` .
Here FM is an array with 6 elements, which correspond to
North(X), East(Y), Downward(Z), Horizontal(H) components,
Inclination(I) and Declination(D).