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14. Generic Quadric. Code: QUA

      A QUA is a quadric surface defined by a 2nd degree equation F(x,y,z) = 0.
      Each QUA is defined by 10 numbers:
      A_xx, A_yy, A_zz, A_xy, A_xz, A_yz, A_x, A_y, A_z, A_0
      corresponding to the equation:
      A_xx x^2 + A_yy y^2 + A_zz z^2 + A_xy xy + A_xz xz + A_yz yz +
          + A_x x + A_y y + A_z x + A_0 = 0
      A QUA definition extends over two cards in default fixed format,
      and over 4 cards in high-accuracy body fixed format.

      Example in default fixed format:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7..
QUA 27 0.0025 0.04 0.0064 0.0 0.0 0.0 0.055 0.64 0.0256 1.8881
* (an ellipsoid centred at x = 11 cm, y = 8 cm, z = -2 cm, with
* a semi-axis 20 cm long parallel to x, one 5 cm long parallel to y and
* one 12.5 cm long parallel to z)
The same example in high-accuracy body fixed format:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+.
QUA 27 0.0025 0.04 0.0064 0.0 0.0 0.0 0.055 0.64 0.0256 1.8881 The same body, described in free format: QUA Elipsoid 0.0025 0.04 0.0064 0.0 0.0 0.0 0.055 0.64 0.0256 1.8881 NOTE +---------------------------------------------------------------------+ | Whenever it is possible, the following bodies should be preferred: | | PLA, QUA, RPP, SPH, XCC, XEC, XYP, XZP, YCC, YEC, YZP, ZCC, ZEC | | These should indeed make tracking faster, since for them extra | | coding ensures that unnecessary boundary intersection calculations | | are avoided when the length of the next step is smaller than the | | distance to any boundary of the current region. | +---------------------------------------------------------------------+

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