regula falsi

gistfile1.scala

  def regulaFalsi(eps:Double)(from:Double, to:Double, f: Double => Double) : Double = {
    var i = 1000
    var a = from
    var fa = f(a)
    var b = to
    var fb = f(b)
    var c = a - fa * (b-a)/(fb-fa)
    var fc = f(c)
    while (abs(fc)>eps && b-a > eps && {i-=1;i} > 0){
      println(a,b,c,fa,fb,fc)
      if (fa*fc < 0){
        b = c
        fb = fc
      } else {
        a = c
        fa = fc
      }
      c = a - fa *(b-a)/(fb-fa)
      fc = f(c)
    }
    c
  }

how about this instead?

def regulaFalsi(f: Double => Double)(from:Double, to:Double, eps:Double) : Double = {
  def step(i: Int, a: Double, fa: Double, b: Double, fb: Double): Double = {
    val c = c = a - fa *(b-a)/(fb-fa)
    val fc = f(c)
    if(abs(fc)>eps && b-a > eps && i > 0){
      println(a,b,c,fa,fb,fc)
      if (fa*fc < 0){
        step(i-1, a, fa, c, fc)
      } else {
        step(i-1, c, fc, b, fb)
      }
    } else c
  }
  step(1000, from, f(from), to, f(to))
}

DISCLAIMER: I didn't even try to compile this