7.11 Geometrical operations

cmcenter( ): Move the Nbody object in order to center the mass center at the origin.

cvcenter( ): Center the center of velocities at the origin.

histocenter( [rbox],[nb])

Move the Nbody object in order to center the higher density region found near the mass center. The higher density region is determined with density histograms.

rbox: box dimension, where to compute the histograms (default=50)
nb: number of bins for the histograms (default=500)

hdcenter( ): Move the Nbody object in order to center the higher density region found. The higher density region is the maximum of variable rho.

translate( dx,[mode])

Translate the positions or the velocities of the object.

dx: translation vector ( $3\times 1$ Float0 Numeric array)
mode: 'p'= translate the positions, 'v'= translate the velocities (default='p')

rotate( [angle],[mode],[axis])

Rotate the positions and/or the velocities of the object around a specific axis.

angle: rotation angle in radian (default=0)
mode: 'p'= rotate only the positions, 'v'=rotate only the velocities, 'a'=rotate the positions and velocities (default='a')
axis: axis of rotation : 'x', 'y', 'z' or (default='x')

rotate2( [angle],[axis],[point])

Rotate the positions and/or the velocities of the object around a specific axis. This function rotate positions and velocities

angle: rotation angle in radian (default=0)
axis: rotation axis
point: rotation center

align( axis,[mode],[sgn],[fact])

Rotate the object in order to align the axis axis with the

axis.

axis: axis to align :
mode: 'p'= rotate only the positions, 'v'=rotate only the velocities, 'a'=rotate the positions and velocities (default='a')
sgn: '+': normal rotation, '-': reverse sense of rotation (default='+')
fact: multiply the rotation angle by a factor fact (default=None)

align2( [axis1=[1,0,0]],[axis2=[0,0,1]],point=[0,0,0])

Rotate the object in order to align the axis1 axis1 with the axis2 axis2.

axis1: first axis
axis2: second axis
point: center of rotation

spin( [omega=None],[L=None],[j=None],[E=None])

Spin the object with angular velocity "omega" (rigid rotation). Omega is a 1 x 3 array object. If L (total angular momentum) is explicitely given, compute Omega from L (1 x 3 array object).

omega: first axis
L: desired angular momentum
j: desired energy fraction in rotation
E: Total energy (without rotation)

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