Information about the format of checkpoint binary files

In case you want to read / write the binary checkpoint files yourself, the following chapter describes the format of these files. There exist 3 different types of checkpoint files for each species:

• [particles](/picmc/checkpoint_format#Particles checkpoint)
• [averages](/picmc/checkpoint_format#Averages checkpoint)
• [materials](/picmc/checkpoint_format#Materials checkpoint)

Particles checkpoint

The first value in the particles checkpoint is:

• 1 integer (4 bytes) - number of quads in the file

Each quad consists of the following values:

• 3 doubles (8 bytes each) - x, y and z coordinate of the lower left back point of the quad
• 3 doubles - length of the quad in x, y and z direction
• 3 integers - number of cells of the quad in x, y and z direction
• 1 double - NREAL value for the given species
• 1 integer - number of particles inside the quad

Each particle inside the quad is described by:

• 3 doubles - x, y and z coordinate relative to lower left back point of the quad
• 3 doubles - velocity in x, y and z direction
• 1 float - timeleft
• 1 integer - number

Averages checkpoint

Materials checkpoint