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## Order of Arguments

Arguments of a ScaLAPACK routine appear in the following order:

- arguments specifying options,
- problem dimensions,
- array or scalar arguments defining the input data; some of them may be overwritten by results,
- other array or scalar arguments returning results,
- work arrays (and associated array dimensions), and
- diagnostic argument INFO.

Note that not every category is present in each of the routines.

When defining each of these categories of arguments, ScaLAPACK distinguishes between local and global data. On entry to a ScaLAPACK routine, local input arguments may have different values on each process in the process grid. Similarly, local output arguments may be assigned different values on different processes in the process grid on exit from the ScaLAPACK routine.

Global input arguments must have the same value on each process in the process grid on entry to a ScaLAPACK routine. If this is not the case, most routines will call `PXERBLA` and return. Global output arguments are assigned the same value on all processes in the process grid on exit from a ScaLAPACK routine.