star-cem

commit c7486e46c1f613b85125f5436ef99ad9671e57a5
parent fe71ca556aa00327f7cbc59d231cbea87bcaf77b
Author: Christophe Coustet <christophe.coustet@meso-star.com>
Date:   Wed, 10 Jun 2026 17:24:27 +0200

Rename zenith in elevation in API and code

As zenith was defined "positive towards the sky", it was really what is
commonly defined as elevation.

Diffstat:
M
src/scem.h
 | 
4
++--
M
src/scem_main.c
 | 
4
++--
M
src/scem_meeus.c
 | 
2
+-
M
src/scem_psa.c
 | 
2
+-
M
src/test_scem_sun_position.c
 | 
2
+-

5 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/src/scem.h b/src/scem.h
@@ -39,7 +39,7 @@ enum scem_sun_algo {
 /* Sun position */
 struct scem_sun_pos {
   /* In [-PI/2, PI/2]. Positive toward the sky */
-  double zenith; /* [rad] */
+  double elevation; /* [rad] */
 
   /* In [0, 2PI] with 0 aligned with north, PI/2 east, PI south, and 3PI/2 west */
   double azimuth; /* [rad] */
@@ -73,7 +73,7 @@ scem_sun_algo_cstr(const enum scem_sun_algo algo)
 
 BEGIN_DECLS
 
-/* Compute the position of the Sun in local coordinates (zenith and azimuth) for
+/* Compute the position of the Sun in local coordinates (elevation and azimuth) for
  * a given observer at the surface of the Earth (can be extended to other
  * planets if required) i.e. the observer has to be located at the surface for
  * the required date */
diff --git a/src/scem_main.c b/src/scem_main.c
@@ -181,9 +181,9 @@ main(int argc, char** argv)
   }
 
   if(args.radian) {
-    printf("%g %g\n", pos.zenith, pos.azimuth);
+    printf("%g %g\n", pos.elevation, pos.azimuth);
   } else {
-    printf("%g %g\n", MRAD2DEG(pos.zenith), MRAD2DEG(pos.azimuth));
+    printf("%g %g\n", MRAD2DEG(pos.elevation), MRAD2DEG(pos.azimuth));
   }
 
 exit:
diff --git a/src/scem_meeus.c b/src/scem_meeus.c
@@ -202,7 +202,7 @@ sun_position_from_earth_meeus
 
   /* Zenital angle: angle between the horizontal plane and the Sun direction */
   latitude_rad = MDEG2RAD(pos->latitude /* [deg] */);
-  sun->zenith /* [rad] */ = asin
+  sun->elevation /* [rad] */ = asin
     ( sin(latitude_rad)*sin(celestial.declination)
     + cos(latitude_rad)*cos(celestial.declination)*cos(H_rad));
 
diff --git a/src/scem_psa.c b/src/scem_psa.c
@@ -155,7 +155,7 @@ sun_pos_local_coords
   zenith_rad += parallax;
 
   sun->azimuth = fmod(azimuth_rad, 2 * PI);
-  sun->zenith = PI * 0.5 - fmod(zenith_rad, 2 * PI);
+  sun->elevation = PI * 0.5 - fmod(zenith_rad, 2 * PI);
 }
 
 /*******************************************************************************
diff --git a/src/test_scem_sun_position.c b/src/test_scem_sun_position.c
@@ -69,7 +69,7 @@ test_api(void)
     CHK(scem_sun_position_from_earth(&utc, &pos, algo, &sun) == RES_OK);
     printf("%s - zenith: %g°; azimuth: %g°\n",
       scem_sun_algo_cstr(algo),
-      MRAD2DEG(sun.zenith),
+      MRAD2DEG(sun.elevation),
       MRAD2DEG(sun.azimuth));
   }
 }