[GRASS-dev] [GRASS GIS] #2941: r.sun: wrong sign in equation of time

[GRASS GIS]

#2941: r.sun: wrong sign in equation of time
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 Reporter:  tomhuld      |      Owner:  grass-dev@…
     Type:  defect       |     Status:  new
 Priority:  normal       |  Milestone:  7.0.4
Component:  Default      |    Version:  unspecified
 Keywords:               |        CPU:  Unspecified
 Platform:  Unspecified  |
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 Bug report ticket #2876 by fabriziosossan reported a problem with the
 equation of time in r.sun, whereby the calculation of the solar time from
 the clock (civil) time is wrong. The problem was fixed with a patch for
 GRASS 6, but as far as I know there the fix was not applied to GRASS 7.

 I would like to suggest the following patch for r.sun/main.c. Since this
 is my first patch for GRASS, apologies if I'm doing it worng.

 --- main.c      (revision 67790)
 +++ main.c      (working copy)
 @@ -1766,7 +1766,7 @@
          * "local clock time". */
         dayRad = 2. * M_PI * day / 365.25;
         locTimeOffset =
 -           -0.128 * sin(dayRad - 0.04887) - 0.165 * sin(2 * dayRad +
 +           +0.128 * sin(dayRad - 0.04887) + 0.165 * sin(2 * dayRad +
                                                          0.34383);

         /* Time offset due to timezone as input by user */

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2941>
GRASS GIS <https://grass.osgeo.org>