temperature conversion functions

1 files changed, 47 insertions, 0 deletions

diff --git a/unit.c b/unit.c
index de24dc3..d1e487d 100644
--- a/unit.c
+++ b/unit.c
@@ -18,6 +18,9 @@
 /* Seconds per minute. */
 #define SEC_PER_MIN 60.0
 
+/* Zero Celsius in Kelvin. */
+#define ZERO_C 273.15
+
 
 AngularSpeed
 rad_per_sec(double x) {
@@ -108,6 +111,50 @@ as_psi(Pressure x) {
 }
 
 
+Temperature
+kelvin(double x) {
+	return x;
+}
+
+Temperature
+celsius(double x) {
+	return x + ZERO_C;
+}
+
+Temperature
+fahrenheit(double x) {
+	double c;
+
+	c = (x - 32.0) * 5.0 / 9.0;
+	return c + ZERO_C;
+}
+
+Temperature
+rankine(double x) {
+	return x * 5.0 / 9.0;
+}
+
+double
+as_kelvin(Temperature t) {
+	return t;
+}
+
+double
+as_celsius(Temperature t) {
+	return t - ZERO_C;
+}
+
+double
+as_fahrenheit(Temperature t) {
+	return as_celsius(t) * 9.0 / 5.0 + 32.0;
+}
+
+double
+as_rankine(Temperature t) {
+	return t * 9.0 / 5.0;
+}
+
+
 Volume
 cubic_centimetre(double x) {
 	return x * 1e-6;