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

[GRASS GIS]

#2941: r.sun: wrong sign in equation of time
--------------------------+-------------------------
  Reporter:  tomhuld      |      Owner:  grass-dev@…
      Type:  defect       |     Status:  new
  Priority:  normal       |  Milestone:  7.0.4
 Component:  Default      |    Version:  unspecified
Resolution:               |   Keywords:
       CPU:  Unspecified  |   Platform:  Unspecified
--------------------------+-------------------------
Description changed by neteler:

Old description:

> 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 */

New description:

 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: <http://trac.osgeo.org/grass/ticket/2941#comment:1>
GRASS GIS <https://grass.osgeo.org>