Bug #1449

Envelope task #1438: === Physics ===

Feature #1289: == Instrument (beam, resolution, detector) ==

Apply detector resolution function can give negative results

Added by herck over 3 years ago. Updated about 3 years ago.

Status:ArchivedStart date:03 Jun 2016
Priority:HighDue date:
Assignee:herck% Done:

0%

Category:-
Target version:Sprint 31

Description

Reproduce:
use HexCylinders.py from gisas/support/015_AnatolyBerezkin and add the following line to create_simulation():
simulation.setDetectorResolutionFunction(ResolutionFunction2DGaussian(0.0005, 0.0005))

History

#1 Updated by wuttke over 3 years ago

  • Priority changed from Normal to High
  • Parent task set to #1289

#2 Updated by herck over 3 years ago

  • Description updated (diff)
  • Status changed from Sprint to Resolved

Negative values arise as a result of the finite precision in the fft's. In special cases, as in the given example, where big plateaus with zero values are interspersed with high and narrow peaks, the convolution using fft gives some quantization noise.
Current solution: truncate negative values.
Note that this noise is quite small compared to the signal, so this should not influence simulation results.

#3 Updated by herck about 3 years ago

  • Status changed from Resolved to Archived

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