Change a method to private and use another overloaded version instead - scala

Question

Code:
object Integral {
def approx(start: Double, end: Double, nIntervals: Int)(f: Double => Double): Double = {
val delta = (end - start) / nIntervals
val halfDelta = delta / 2
val xs = start until end by delta
xs.map(x => f(x + halfDelta) * delta).sum
}
def approx(startEnd: Array[Double], nIntervas: Int)(f: Double => Double): Double = {
require(startEnd.length == 2)
val startEndSorted = startEnd.sorted
val res = approx(startEndSorted(0), startEndSorted(1), nIntervas)(f)
if(startEndSorted == startEnd) res else (-res)
}
}
object IntegralTest {
def f1(x: Double) = {
math.pow(x, 3) - 6 * x
}
println(Integral.approx(0, 3, 6)(f1))
println(Integral.approx(0, 1, 60000)(f1))
def f2(x: Double) = {
math.sqrt(1 - x * x)
}
println(Integral.approx(0, 1, 60000)(f2))
println(math.Pi / 4)
println(Integral.approx(0, 3, 60000)({
(x: Double) => x - 1
}))
println(Integral.approx(1, 2, 5)({
(x: Double) => 1 / x
}))
// test the exponential function
println(Integral.approx(1, 3, 60000)(math.exp))
println(math.exp(3) - math.exp(1))
}
I want to make approx(start: Double, end: Double, nIntervals: Int)(f: Double => Double): Double private and change all the reference to it to approx(startEnd: Array[Double], nIntervas: Int)(f: Double => Double): Double, is there a way to do this safely and hassle-free in intellij?
Update
I soon realized that for this specific case I could have handled it in a better way (by recursion):
def approx(start: Double, end: Double, nIntervals: Int)(f: Double => Double): Double = {
if(start > end) {
-approx(end, start, nIntervals)(f)
} else {
val delta = (end - start) / nIntervals
val halfDelta = delta / 2
val xs = start until end by delta
xs.map(x => f(x + halfDelta) * delta).sum
}
}
But I am still interested in finding out how to refactor the old problematic code because it might be useful in the future.

Answer 1

I don't know if the fact you use it for Scala changes anything, but you should be able to right-click on a function, and Change method signature to the one you want (so you wouldn't replace function1 by function2 per se, but rather modify f1 to match f2).
Edit: This won't work as per Ben comment. Leaving anyway for the sake of mentioning the functionality.