Fix temperature rounding issues

Temperatures can actually be negative, which means that rounding by
adding 0.5 and casting to 'int' is not correct.

We could use '(int)(rint(val))' instead, but the only place we care
about might as well just print out the floating point representation
with a precision of two digits instead.  So if you have a dive computer
that gives you the precision, you might see '3.5˚C' as the temperature.

Remove the helper functions that nobody uses and that get the rounding
wrong anyway.

Reported-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

2 files changed, 1 insertions, 22 deletions

diff --git a/dive.h b/dive.h
index e76b6dadf..fc82f5e43 100644
--- a/dive.h
+++ b/dive.h
@@ -179,27 +179,6 @@ static inline unsigned long C_to_mkelvin(double c)
 	return c * 1000 + 273150.5;
 }
 
-static inline int to_C(temperature_t temp)
-{
-	if (!temp.mkelvin)
-		return 0;
-	return mkelvin_to_C(temp.mkelvin) + 0.5;
-}
-
-static inline int to_F(temperature_t temp)
-{
-	if (!temp.mkelvin)
-		return 0;
-	return mkelvin_to_F(temp.mkelvin) + 0.5;
-}
-
-static inline int to_K(temperature_t temp)
-{
-	if (!temp.mkelvin)
-		return 0;
-	return (temp.mkelvin + 499)/1000;
-}
-
 static inline double psi_to_bar(double psi)
 {
 	return psi / 14.5037738;
diff --git a/profile.c b/profile.c
index 18987c274..4aa70ad11 100644
--- a/profile.c
+++ b/profile.c
@@ -894,7 +894,7 @@ static void plot_single_temp_text(struct graphics_context *gc, int sec, int mkel
 
 	deg = get_temp_units(mkelvin, &unit);
 
-	plot_text(gc, &tro, sec, mkelvin, "%d%s", (int)(deg + 0.5), unit);
+	plot_text(gc, &tro, sec, mkelvin, "%.2g%s", deg, unit);
 }
 
 static void plot_temperature_text(struct graphics_context *gc, struct plot_info *pi)