Magix Plus & Magix XL 
Magnetic and Gravity Modeling
General
The MAGIX family of software models
data in 2, 2.5, and 2.75 dimensional earth models
consisting of bodies and layers whose forward response
matches the input data along a single profile line.
All the software packages in the
MAGIX family use a generalized "2.75 dimensional" model
to compute the theoretical gravity and magnetic
response. The 2.75 D model represents the geology as
polygonal prisms with horizontal axes and either finite
or infinite extent in the strike direction. The strike
direction need not be perpendicular to the plane of the
profile. The forward model is based on the Rasmussen and
Pedersen method.
The MAGIX family uses Inmanstyle
ridge regression for the inversion calculations. This is
a nonlinear least squares approach for obtaining the
model which best fits the observed data. Parameters that
may vary during an inversion include density,
susceptibility, or the vertex of a body in X, Z or X any
Z position.
The magnetic calculations take into
account both induced magnetization and possible
permanent magnetization. The remanent magnetization is
entered as the inclination, declination and the
Koenigsberger ratio.
Data are read into the program via
ASCII files of various formats. Options are available
for data input including profile selection from maps and
resampling of long profiles.
Data parameters are set using
interactive dialog boxes. The program can calculate
Magnetic or Magnetic Gradient data for Total Field, x, y
or z components. Magnetic susceptibility units supported
now include cgs, microcgs and SI units.
Gravity density units include both
gm/c3, and kg/m3 and calculations can be set to micro
or milligals.
Survey geometry is added by using a
interactive graphics screen or text dialog boxes. The
graphical geometry editing allows for animation of
selected parameters. This helps the user understand the
parameters required to specify the profiles in the 2.75D
space.
Options for geometry include a
profile or XY mode of coordinates and strike directions
that is not perpendicular with the profile direction.
Body entry is done using the mouse
in an interactive graphics screen. Keyboard entry into
spreadsheet style editors is also available. Bodies are
entered as a series of vertices. A variety of
calculation modes can be chosen, one of which is
realtime update of the synthetic response with changes
in the model.
Body editing allows for features
like vertex locking and homing, multiple vertex locking,
susceptibility and density editing and strike extent
editing. Bodies can be rotated, deleted, copied and
split. All body editing can be done in the interactive
graphics screen by mouse click and drag operations.
Keyboard entry and editing of
bodies permits the user to enter model parameters from
external sources and define bodies based on know values.
Model parameters can be saved to
files for import with new data sets or comparisons of
different models for the same data set. Models used for
gravity data sets can be imported with magnetic data
sets to function as starting models.
A variety of Output functions
enable the user to save field data, synthetic data and
model parameters to files for import or processing in
third party software.
Graphical viewing is an integral
part of the program and the user has full control over
colours, axes labels, scales and data symbols. Auto
scaling is built in with full user control over items to
be scaled.
The regional editing allows
graphical selection of the regional. The regional may
also be calculated by fitting a polynomial to selected
data points or groups of data points.
Model and data sections can be
annotated by using the label editing sections. Features
include mouse controllable sizing, placement and arrow
editing. All labels can be set to a specific size,
multiplied by a factor, or constants added to increase
or decrease size.
The following table lists the
differences between the programs in the Magix family.
Except for these differences the programs work the same.
Features 
Magix Plus v3 
Magix XL v3 
Maximum number of bodies 
25 
200 
Maximum number of vertices 
240 
2000 
Maximum number of data
points 
200 
1000 
Regional removal by fitting
a polynomial curve to data 
N 
Y 
File Input/Output within
the Interactive Graphics Interpretation 
N 
Y 
Invert for density or
susceptibility for all or selected bodies only 
N 
Y 
Support for the input and
output of LCT data and model files 
N 
Y 
Resample of profile data
using minimum curvature gridding 
N 
Y 
Reselection of profile from
map for XY data stored in map form 
N 
Y 
Graphical Geometry Editing 
N 
Y 
Standard Components
MAGIXPlus or MAGIX XL and
instruction manual.
