usage: pp2d [-hm]

Displays animations of two dimensional particle motion

   Flags: -h   help
          -m   monochrome

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pp2d expects the following formatted input on standard input:
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       <np>                          ! Number of particles
       <size_1>                      ! Relative display size of particle 1
       <size_2>                      ! Relative display size of particle 2
                   .
                   .
                   .
       <size_np>                     ! Relative display size of particle np
       <t_1>                         ! First display time
       <x_1_1>  <y_1_1>  <z_1_1>     ! Coordinates of particle 1 at t_1
       <x_1_2>  <y_1_2>  <z_1_2>     ! Coordinates of particle 2 at t_1
                   .
                   .
                   .
       <x_1_np> <y_1_np> <z_1_np>    ! Coordinates of particle np at t_1
       <t_2>                         ! Second display time
       <x_2_1>  <y_2_1>  <z_2_1>     ! Coordinates of particle 1 at t_2
       <x_2_2>  <y_2_2>  <z_2_2>     ! Coordinates of particle 2 at t_2
                   .
                   .
                   .
       <x_2_np> <y_2_np> <z_2_np>    ! Coordinates of particle np at t_2
       <t_3>                         ! Third display time
                   .
                   .
                   .

  All values are expected to be real numbers except for <np> which is
  an integer.  Note that 3 coordinates per particle are expected
  although the z coordinate will be ignored.

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pp2d keyboard assigments (commands are case-insensitive):
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  ESC:               Exit program
  p:                 Pause/continue animation

  z:                 Zoom-in on solution domain
  x:                 Zoom-out on solution domain

  a:                 Enlarge marker size
  s:                 Reduce marker size

  q:                 Enlarge window size
  w:                 Reduce window size

  up-arrow (k):      Pan up
  down-arrow (j):    Pan down
  left-arrow (h):    Pan left
  right-arrow (l):   Pan right

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Miscellaneous
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The initial (default) viewing region is: -2 <= x <= 2  -2 <= y <= 2
The base marker size is 5 pixels
Markers can range from 3 to 20 pixels in size