Opened 5 years ago
Closed 5 years ago
#484 closed defect (fixed)
lamellarPC is precision limited
Reported by: | pkienzle | Owned by: | richardh |
---|---|---|---|
Priority: | critical | Milestone: | SasView 4.0.0 |
Component: | SasView | Keywords: | |
Cc: | Work Package: | SasModels Redesign |
Description
Adapt the Lamellar PC calculation to use less precision limited math.
That means replacing ww = exp(…) with ww-1 = expm1(…), which can be calculated without loss of precision. Similarly, 1 - cos(x) for cos(x) near zero can be replaced with 2*sin^{2}(x).
The alternative is to force lamellarPC to use double or quad precision even if the rest of the calculations are in single precision.
Use compare -longdouble to evaluate a model with quad precision.
Change History (4)
comment:1 Changed 5 years ago by butler
- Priority changed from minor to critical
comment:2 Changed 5 years ago by ajj
- Owner set to richardh
- Status changed from new to assigned
comment:3 Changed 5 years ago by smk78
Is this ticket still valid now model has changed?
comment:4 Changed 5 years ago by ajj
- Resolution set to fixed
- Status changed from assigned to closed
Forcing double precision. Model is still a bit cranky, but can't be helped.
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probably should be part of the core model conversion process. As I understand it this "works" so maybe only critical and not blocker for the release?