[MATH-248] Multiplying sparse matrices is slow

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.0
• Assignee: Luc Maisonobe
• Reporter: Christian Semrau
• Created: 22/Feb/09 19:53
• Updated: 23/Apr/09 02:26
• Resolved: 05/Apr/09 16:54

Description

The multiplication of sparse real matrices is very slow compared to real matrices: Ten times as slow for size 200, four times as slow for size 400. The time is independent of the number of nonzero entries, because the general algorithm inherited from AbstractRealMatrix is used. I suggest using a specialized multiplication algorithm for matrices that are "sparse enough", walking only over the nonzero entries in one of the matrices.