All ScaLAPACK routines assume that the data has been distributed on the process grid prior to the invocation of the routine. Detailed descriptions of the appropriate calling sequences for each of the ScaLAPACK routines can be found in the leading comments of the source code or in Part ii of this users guide. The required data distribution for the ScaLAPACK routine, as well as the amount of input error checking to be performed, is described in Chapter 4. For debugging hints, the user should refer to Chapter 7.