GEMMW: A portable level 3 BLAS Winograd variant of Strassen’s matrix- matrix multiply algorithm. The authors describe a set of routines called GEMMW for implementing a Winograd variant of Strasser’s matrix-matrix multiply algorithm. The aim is the multiplication of large, full, explicitly stored matrices. Both real and complex matrices are considered. Parallel environments with distributed memory are studied carefully. All matrix sizes are allowed and the source codes are available from LINALG/GEMMW. SHAR in NETLIB.