[ https://issues.apache.org/jira/browse/SYSTEMML-1644?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Matthias Boehm reassigned SYSTEMML-1644: ---------------------------------------- Assignee: Matthias Boehm > Incorrect results on multi-threaded dense-dense matrix multiply w/ short lhs > ---------------------------------------------------------------------------- > > Key: SYSTEMML-1644 > URL: https://issues.apache.org/jira/browse/SYSTEMML-1644 > Project: SystemML > Issue Type: Bug > Reporter: Matthias Boehm > Assignee: Matthias Boehm > > The following matrix multiply expression yields incorrect results compared to > R when run with multi-threaded operations but correct results with > single-threaded operations. > {code} > # X is dense 2023 x 1987 matrix > # t(U) is dense 10 x 2023 matrix > R = t(U) %*% X; > {code} > Note: This affects any dense-dense matrix multiplication with short > left-hand-side (of <=16 rows) and wide right-hand-side (of #features > the > cache block size of 1024 columns). Such operations occur for example in > Mlogreg and Kmeans with a number of classes/centroids 1 < x <= 16 and a > feature matrix with ncol(X) > 1024. -- This message was sent by Atlassian JIRA (v6.3.15#6346)