`zgemm:`procedure`xGEMM`performs matrix-matrix multiply-add operation of the form`C := alpha*op( A )*op( B ) + beta*C`, where`op( X )`is one of`op( X ) = X`or`op( X ) = X'`.`ALPHA`and`BETA`are scalars, and`A`,`B`and`C`are matrices, with`op( A )`an`M x K`matrix,`op( B )`a`K x N`matrix and`C`an`M x N`matrix.