Data commit

Task/Roots-of-a-function/CoffeeScript/roots-of-a-function-1.coffee

@@ -0,0 +1,35 @@
+print_roots = (f, begin, end, step) ->
+  # Print approximate roots of f between x=begin and x=end,
+  # using sign changes as an indicator that a root has been
+  # encountered.
+  x = begin
+  y = f(x)
+  last_y = y
+
+  cross_x_axis = ->
+    (last_y < 0 and y > 0) or (last_y > 0 and y < 0)
+
+  console.log '-----'
+  while x <= end
+    y = f(x)
+    if y == 0
+      console.log "Root found at", x
+    else if cross_x_axis()
+      console.log "Root found near", x
+    x += step
+    last_y = y
+
+do ->
+  # Smaller steps produce more accurate/precise results in general,
+  # but for many functions we'll never get exact roots, either due
+  # to imperfect binary representation or irrational roots.
+  step = 1 / 256
+
+  f1 = (x) -> x*x*x - 3*x*x + 2*x
+  print_roots f1, -1, 5, step
+  f2 = (x) -> x*x - 4*x + 3
+  print_roots f2, -1, 5, step
+  f3 = (x) -> x - 1.5
+  print_roots f3, 0, 4, step
+  f4 = (x) -> x*x - 2
+  print_roots f4, -2, 2, step

Task/Roots-of-a-function/CoffeeScript/roots-of-a-function-2.coffee

@@ -0,0 +1,13 @@
+> coffee roots.coffee
+-----
+Root found at 0
+Root found at 1
+Root found at 2
+-----
+Root found at 1
+Root found at 3
+-----
+Root found at 1.5
+-----
+Root found near -1.4140625
+Root found near 1.41796875