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snapinert - calculate momentum of inertia of a snapshot


snapinert in=snapshot out=out-file [parameter=value]


snapinert calculates the momentum of inertia of a snapshot. The output is ASCII and consists of three parts:

1) Time

2) Moment of inertia tensor

3) Eigenvalues and Eigenvectors of (2) .

The program snapkinem(1NEMO) does similar things - ideas should be combined.


The following parameters are recognized in any order if the keyword is also given:
input file, must be in SnapShot(5) format [no default].
output file, ASCII format [no default]
Only data frames with time values within time-range, which is of the form, eg, "1.0:1.5,2.5,3.0", will be translated. [default: all].
The value of expression is used to compute the center of the coordinate and also the momentum of inertia. expression is a real-valued C language expression over the real values x, y, z, vx, vy, vz, phi, m, t, and the integer value i. [default : 1]
Logical if the result is weight-normalized. [default: t].
Usually snapinert gives the result in a (barely) human-readable format. This option forces all values printed in one line, so that other programs such as MONGO, TABMATH(NEMO1) and AWK can easily access it. [default: f].

See Also

snapkinem(1NEMO) , snaprect(1NEMO) , bodytrans(3NEMO)


From some reasons the source library of the "Numerical Recipes in C" is required to compile snapinert. Since the standard NEMO package does not include the Numerical Recipes, on sites that does not have the sources of Numerical Recipes snapinert cannot be compiled. The Makefile assumes the source library to exist in $NUMRECPATH.


Jun Makino

Update History

30-Jun-88    V1.0: Created    JM
7-jul-89    V1.2: get_snap(), oneline= keyword is now tab=     PJT

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