object PercentChangeDemo {
def percentChange(x: Double, y: Double): Double =
((y - x) / math.abs(x)) * 100.0
def describeChange(x: Double, y: Double): String = {
val pct = percentChange(x, y)
pct match {
case p if p > 0 =>
f"From $x%.1f to $y%.1f is a $p%.2f%% increase (+$p%.2f%%)"
case p if p < 0 =>
f"From $x%.1f to $y%.1f is a ${math.abs(p)}%.2f%% decrease ($p%.2f%%)"
case _ =>
f"From $x%.1f to $y%.1f is no change"
}
}
def main(args: Array[String]): Unit = {
println(describeChange(-80.0, 120.0))
println(describeChange(120.0, 30.0))
println(describeChange(60.0, 60.0))
}
}
/*
run:
From -80.0 to 120.0 is a 250.00% increase (+250.00%)
From 120.0 to 30.0 is a 75.00% decrease (-75.00%)
From 60.0 to 60.0 is no change
*/
