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# Common Errors in Calling ScaLAPACK Routines

The user must read the leading comments of a ScaLAPACK routine before invoking the routine. The wording of the leading comments is explained in Chapter 4. Basic terminology is explained in the Glossary and List of Notation.

For the benefit of less experienced programmers, we provide a list of common programming errors in calling a ScaLAPACK routine. These errors may cause the ScaLAPACK routine to report a failure, as described in section 7.4 ; they may cause an error to be reported by the system; or they may lead to wrong results -- see also section 7.5.

- Wrong number of arguments
- Arguments in the wrong order
- Argument of the wrong type (especially real and complex arguments of the wrong precision)
- Wrong dimensions for an array argument
- Insufficient space in a workspace argument
- Failure to assign a value to an input argument
- Routine designed for homogeneous computers was executed on a heterogeneous system (see section 6.2)

Some modern compilation systems, as well as software tools such as the Fortran 77 syntax checker `ftnchek` (freely available on netlib) and the portability checker in Toolpack [105], can check that arguments agree in number and type; and many compilation systems offer run-time detection of errors such as an array element out-of-bounds or use of an unassigned variable.