Moves the file pointer on a PETSc binary file.
fd - the file
off - number of bytes to move. Use
PETSC_BINARY_SCALAR_SIZE, etc. in your calculation rather than sizeof() to compute byte lengths.
whence - if
PETSC_BINARY_SEEK_SETthen off is an absolute location in the file if
PETSC_BINARY_SEEK_CURthen off is an offset from the current location if
PETSC_BINARY_SEEK_ENDthen off is an offset from the end of file
offset - new offset in file
Integers are stored on the file as 32 long, regardless of whether
they are stored in the machine as 32 or 64, this means the same
binary file may be read on any machine. Hence you CANNOT use
to determine the offset or location.