diff --git a/logic.go b/logic.go
new file mode 100644
index 0000000..01db99b
--- /dev/null
+++ b/logic.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"math"
+)
+
+func calc_fan_speed(temp float64) float64 {
+	switch g_opt_mode {
+	case mode_Default:
+		return math.Log10(temp/40.0) / 0.3 * g_max_fan_speed //quiet but not so cool
+	case mode_Aggressive:
+		return math.Log10(temp/30.0) / 0.35 * g_max_fan_speed //cooler but also louder
+	}
+	return g_min_fan_speed
+}
+
+//check temp, set speed
+func DoWork() {
+	f := GetAverageTemp()
+	verbOutp("Average temperature:", f)
+	speed := GetFanSpeed()
+	verbOutp("Fan Speed:", speed)
+
+	rpm := calc_fan_speed(f)
+	SetFanSpeed(rpm)
+}