[GRASS-dev] [GRASS GIS] #2854: results in winGRASS7 32bit vs 64bit: should they be identical?

[GRASS GIS]

#2854: results in winGRASS7 32bit vs 64bit: should they be identical?
---------------------+---------------------------------
  Reporter:  hellik  |      Owner:  grass-dev@…
      Type:  defect  |     Status:  new
  Priority:  normal  |  Milestone:  7.0.3
 Component:  Raster  |    Version:  svn-releasebranch70
Resolution:          |   Keywords:
       CPU:  x86-64  |   Platform:  MSWindows 7
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Comment (by hellik):

 Replying to [comment:1 neteler]:
 > Please also add the "r.univar -e ..." output of
 >
 > {{{
 > r.mapcalc "difftestepsilon_values = if( abs( accum_wg32bit at watershedtest
 - accum_wg64bit at watershedtest  ) <= 1.0e-15 , 1 ,
 accum_wg32bit at watershedtest - accum_wg64bit at watershedtest )"
 > }}}
 >
 > to see the actual differences and not 100. Thanks.

 tested with r.slope.aspect


 {{{
 r.slope.aspect elevation=elevation at PERMANENT slope=slope_wg32bit
 aspect=aspect_wg32bit
 r.slope.aspect elevation=elevation at PERMANENT slope=slope_wg64bit
 aspect=aspect_wg64bit
 }}}

 {{{
 r.mapcalc expression=diff_slope = slope_wg32bit at slope_test -
 slope_wg64bit at slope_test

 r.univar -e map=diff_slope at slope_test
 total null and non-null cells: 2025000
 total null cells: 5696
 Of the non-null cells:
 ----------------------
 n: 2019304
 minimum: 0
 maximum: 0
 range: 0
 mean: 0
 mean of absolute values: 0
 standard deviation: 0
 variance: 0
 variation coefficient: nan %
 sum: 0
 1st quartile: 0
 median (even number of cells): 0
 3rd quartile: 0
 90th percentile: 0
 }}}

 and also tested with r.topidx

 {{{
 r.topidx input=elevation at PERMANENT output=topidx_wg32bit
 r.topidx input=elevation at PERMANENT output=topidx_wg64bit
 }}}

 {{{
 r.mapcalc expression=diff_topidx_epsilon = if( abs(
 topidx_wg32bit at test_topidx - topidx_wg64bit at test_topidx ) <= 1.0e-15 ,
 null()  , topidx_wg32bit at test_topidx - topidx_wg64bit at test_topidx )
 }}}

 {{{
 r.mapcalc expression=diff_topidx_epsilon = if( abs(
 topidx_wg32bit at test_topidx - topidx_wg64bit at test_topidx ) <= 1.0e-15 ,
 null()  , topidx_wg32bit at test_topidx - topidx_wg64bit at test_topidx )

 r.univar -e map=diff_topidx_epsilon at test_topidx
 total null and non-null cells: 2025000
 total null cells: 1920831
 Of the non-null cells:
 ----------------------
 n: 104169
 minimum: -3.55271e-015
 maximum: 3.55271e-015
 range: 7.10543e-015
 mean: -1.67607e-015
 mean of absolute values: 1.7849e-015
 standard deviation: 0
 variance: 0
 variation coefficient: -0 %
 sum: -1.74594561030972e-010
 1st quartile: -1.77636e-015
 median (odd number of cells): -1.77636e-015
 3rd quartile: -1.77636e-015
 90th percentile: -1.77636e-015
 }}}

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2854#comment:5>
GRASS GIS <https://grass.osgeo.org>