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File Formats -
Forward matrix
Description
The forward matrix (.fwd) file
is essentially a matrix in row major order (i.e. all the elements of the
first row appear in sequence before the elements of the second row, and so
forth). The Prolog and header are ASCII, while the matrix itself consists
of double precision (i.e. 8 bytes per number) floating point numbers,
which may be in ascii or binary, as determined by the mode filed of the
header (see below). The data are typcially binary little-endian (Intel) IEEE 754-1985 64-bit format. For EMSE v4.2 and
below, minor revision 3 files were written and read. EMSE v5.0 and above
writes major revision 4 files, but can read both major revision 3 and 4.
In this document we will define major revision 3 and major revision 4
separately, though they are quite similar.
N.B. – Open as binary
In order to read these files properly, you
must open them as binary, as shown in the
example code for the inverse operator file.
Comments
Comment lines are not supported for this
file type.
Major Revision 4
Prolog
|
Name |
Format |
Description |
|
Magic number |
%x |
0x454D5345 |
|
Major revision |
%d |
0x4 |
|
Minor revision |
%d |
0x1 |
|
Type |
%x |
0x4 |
Table A-1
Header
The
header consists of the entries shown in Table A-2 (in mandatory sequence):
|
Name |
Format |
Description |
|
mode |
%x |
0x200000 if binary data, else ascii data |
|
#rows |
%d |
Number of rows (inner skull vertices) |
|
#columns |
%d |
Number of columns( # data channels) |
|
Tangent
space dimension |
%d |
First 16 bits: 1 or 3 dipoles per location
Last 16 bits used to define if cortical thinning was
used (see example code) |
|
[angle
criterion] |
%f |
If (TangentSpaceDimension & 0x00400000), this field
contains the angle criterion for cortical dipole thinning, else the
field is omitted |
|
[distance criterion] |
%f |
If (TangentSpaceDimension & 0x00400000), this field
contains the distance criterion for cortical dipole thinning, else the
field is omitted |
Data
The
data arein row-wise ordering, i.e. all the elements of a row are stored as
successive 8-byte values before proceeding on to the next row.
Major Revision 3
Prolog
|
Name |
Format |
Description |
|
Major revision |
%d |
3 |
|
Type |
%x |
0x00000010 |
|
Minor revision |
%d |
1 |
Table A-3
Header
The
header is the same as in version 4 (see Table A-2).
Data
The
data are in row-wise ordering, i.e. in binary, all the elements of a row are stored as
successive 8-byte values before proceeding on to the next row.
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