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Bug 1712

Summary: Sub-Optimal code for mixed complex*real products
Product: Eigen Reporter: Christoph Hertzberg <chtz>
Component: Core - matrix productsAssignee: Nobody <eigen.nobody>
Status: CONFIRMED ---    
Severity: Performance Problem CC: chtz, gael.guennebaud
Priority: Normal    
Version: 3.4 (development)   
Hardware: All   
OS: All   
Whiteboard:
Bug Depends on: 1019    
Bug Blocks: 1608    

Description Christoph Hertzberg 2019-05-10 16:54:25 UTC
For column-major matrices A*B, with A complex and B real would be equivalent to multiplying two real matrices where A has twice the height. Currently, Eigen is not able to vectorize this properly. Actually, clang is able to auto-vectorize this (for full FMA usage, sometimes this requires -ffast-math): https://godbolt.org/z/ILd8tL

I guess complex*real could easially be solved by Bug 1019.
But real*complex will require some new logic (essentially, the real matrix would need to have each row duplicated).
Comment 1 Nobody 2019-12-04 18:38:11 UTC
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