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Bug 1639

Summary: Prohibit TriangularSolve for integer types?
Product: Eigen Reporter: Christoph Hertzberg <chtz>
Component: Core - generalAssignee: Nobody <eigen.nobody>
Status: DECISIONNEEDED ---    
Severity: Accuracy Problem CC: chtz, gael.guennebaud, jacob.benoit.1
Priority: Normal    
Version: 3.4 (development)   
Hardware: All   
OS: All   
Bug Depends on:    
Bug Blocks: 1608    

Description Christoph Hertzberg 2018-12-06 23:14:20 UTC
Calculating any decomposition for integer matrices already fails to compile with a static assertion THIS_FUNCTION_IS_NOT_FOR_INTEGER_NUMERIC_TYPES.
Shouldn't we do the same for triangular solvers?
Would that break any (valid) code?
Comment 1 Gael Guennebaud 2018-12-07 09:24:50 UTC
If the diagonal is filled with 1 (including UnitDiag mode), then this is valid, though I don't have use cases in mind.
Comment 2 Christoph Hertzberg 2018-12-07 12:56:24 UTC
Ok, that is true and might be a valid use case. And of course there can be other cases where all integer divisions happen to be exact. 
Maybe we should just document the current behavior (including that it can lead to uncaught divisions by zero).
Comment 3 Nobody 2019-12-04 18:14:24 UTC
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