rectprismmag {gravmagsubs} | R Documentation |
rectprismmag
Description
Calculates the magnetic effect of 3-D rectangular prisms.
Calculates anomalies of N
prisms at M
observation stations.
Stations cannot be positioned inside a prism, or on its edges or faces. Stations cannot be positioned directly below the corners of a prism.
Coordinates of stations and prisms are assumed to share a common coordinate system.
Returns total field magnetic anomaly in nanoteslas (nT).
N.B. Demagnetization effects are ignored in this subroutine.
Usage
rectprismmag(xstation, ystation, zstation, xmin, xmax, ymin, ymax,
zdeep, zshallow, suscvolsi, nrmstr, nrmincl, nrmdecl,
fieldtotal, fieldincl, fielddecl, bycell=FALSE)
Arguments
xstation |
vector of length |
ystation |
vector of length |
zstation |
vector of length |
xmin |
vector of length |
xmax |
vector of length |
ymin |
vector of length |
ymax |
vector of length |
zdeep |
vector of length |
zshallow |
vector of length |
suscvolsi |
vector of length |
nrmstr |
vector of length |
nrmincl |
vector of length |
nrmdecl |
vector of length |
fieldtotal |
vector of length |
fieldincl |
vector of length |
fielddecl |
vector of length |
bycell |
returns |
Value
Returns a matrix of length M
rows.
If bycell=FALSE
, there will be M
rows and 1 column, and the
element in the i
-th row represents the total magnetic anomaly generated
by all N
prisms as observed at the i
-th station.
If bycell=TRUE
, the matrix will have M
rows and N
columns,
with the element [i,j]
representing the anomaly value generated by the
j
-th prism as observed at the i
-th station.
References
Plouff, D., 1975, Derivation of formulas and FORTRAN programs to compute magnetic anomalies of prisms, National Technical Information Service No. PB-243-525, U.S. Department of Commerce, Springfield, VA.
https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB243525.xhtml.
See Also
Examples
#########################################################
## magnetic anomaly of single prism at a single point ##
# location of the point where the magnetic anomaly will be calculated
magstation <- data.frame(x=0, y=0, z=0)
# the rectangular prism is defined by its six edges
prism1 <- data.frame(xmin=-5, xmax=5,
ymin=-5, ymax=5,
zmin=-10, zmax=-5)
susc <- 5 # susceptiblity (SI)
mstr <- 0 # remanent magnetization (A/m)
mincl <- 0 # remanent inclination (deg)
mdecl <- 0 # remanent declination (deg)
ftotal <- 48800 # Earth's field intensity (nT)
fincl <- 60 # field inclination (deg)
fdecl <- 12 # field declination (deg)
maganom <- rectprismmag(magstation$x, magstation$y, magstation$z,
prism1$xmin, prism1$xmax,
prism1$ymin, prism1$ymax,
prism1$zmin, prism1$zmax, susc,
mstr, mincl, mdecl,
ftotal, fincl, fdecl)
#########################################################