Opened 4 years ago

Closed 4 years ago

#2941 closed defect (fixed)

r.sun: wrong sign in equation of time

Reported by: tomhuld Owned by: grass-dev@…
Priority: normal Milestone: 7.0.4
Component: Raster Version: svn-releasebranch70
Keywords: r.sun Cc:
CPU: Unspecified Platform: Unspecified

Description (last modified by neteler)

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 */

Change History (3)

comment:1 Changed 4 years ago by neteler

Description: modified (diff)

comment:2 in reply to:  description Changed 4 years ago by neteler

Component: DefaultRaster
Keywords: r.sun added

Replying to tomhuld:

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,

So far the proposed patch has not been applied. Should it be? From the discussion in ticket #2876 it is not clear to me.

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.

Ideally please submit the diff as an attachment by (in this case) running

# from main source code directory
svn diff raster/r.sun/ > r_sun.diff

(For now, I have reformatted your comment here by protecting it with curly braces.) Should your change be submitted in addition to the patch proposed in ticket #2876 or exclusively your change?

comment:3 Changed 4 years ago by neteler

Resolution: fixed
Status: newclosed
Version: unspecifiedsvn-releasebranch70

Thanks for the patch, applied in r68254 (relbranch70) and r68255 (trunk).

Compare also the equivalent alternative GRASS GIS 7 fix suggested in #2876 (commented on in cited email in ​https://lists.osgeo.org/pipermail/grass-dev/2016-April/079789.html).

Closing.

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