The routines in the IMSL MATH/LIBRARY attempt to detect and report errors and invalid input. Errors are classified and are assigned a code number. By default, errors of moderate or worse severity result in messages being automatically printed by the routine. Moreover, errors of worse severity cause program execution to stop. The severity level and the general nature of the error are designated by an “error type” ranging from 0 to 5. An error type 0 is no error; types 1 through 5 are progressively more severe. In most cases, you need not be concerned with our method of handling errors. For those interested, a complete description of the error-handling system is given in the Reference Material, which also describes how you can change the default actions and access the error code numbers.

A separate error handler is provided to allow users to handle errors of differing types being reported from several nodes without danger of “jumbling” or mixing error messages. The design of this error handler is described more fully in Hanson (1992). The primary feature of the design is the use of a separate array for each parallel call to a routine. This allows the user to summarize errors using the routine error_post in a non-parallel part of an application. For a more detailed discussion of the use of this error handler in applications which use MPI for distributed computing, see the Reference Material.