Parallel ESSL is a scalable mathematical subroutine library that supports parallel processing applications on the SP system and on clusters of RS/6000 workstations. Parallel ESSL supports the Single Program Multiple Data programming model and provides subroutines in six major areas of mathematical computations. It is tuned for optimal performance on the SP system with the SP Switch (16-port or 8-port).

Parallel ESSL provides subroutines in the following computational areas:

- Level 2 PBLAS
- Level 3 PBLAS
- Linear Algebraic Equations
- Eigensystem Analysis and Singular Value Analysis
- Fourier Transforms
- Random Number Generation

The subroutines run under the AIX operating system and can be called from application programs written in Fortran, C, C++, and High Performance Fortran (HPF). On the SP system, PSSP is required.

For communication, Parallel ESSL includes the Basic Linear Algebra Communications Subprograms (BLACS), which use the Parallel Environment (PE) Message Passing Interface (MPI). Communications using the User Space (US) require use of an SP switch. Communications using the Internet Protocol (IP) can use Ethernet, Token Ring, FDDI, SP Switch2, SP Switch, or SP Switch-8.

To order IBM Parallel ESSL for AIX, specify program number 5765-C41. Parallel ESSL requires IBM ESSL for AIX, program number 5765-C42.