Data commit

Task/Active-object/Lua/active-object.lua

@@ -0,0 +1,39 @@
+local seconds = os.clock
+
+local integrator = {
+  new = function(self, fn)
+    return setmetatable({fn=fn,t0=seconds(),v0=0,sum=0,nup=0},self)
+  end,
+  update = function(self)
+    self.t1 = seconds()
+    self.v1 = self.fn(self.t1)
+    self.sum = self.sum + (self.v0 + self.v1) * (self.t1 - self.t0) / 2
+    self.t0, self.v0, self.nup = self.t1, self.v1, self.nup+1
+  end,
+  input = function(self, fn) self.fn = fn end,
+  output = function(self) return self.sum end,
+}
+integrator.__index = integrator
+
+-- "fake multithreaded sleep()"
+-- waits for "duration" seconds calling "f" at every "interval" seconds
+local function sample(duration, interval, f)
+  local now = seconds()
+  local untilwhen, nextinterval = now+duration, now+interval
+  f()
+  repeat
+    if seconds() >= nextinterval then f() nextinterval=nextinterval+interval end
+  until seconds() >= untilwhen
+end
+
+local pi, sin = math.pi, math.sin
+local ks = function(t) return sin(2.0*pi*0.5*t) end
+local kz = function(t) return 0 end
+local intervals = { 0.5, 0.25, 0.1, 0.05, 0.025, 0.01, 0.005, 0.0025, 0.001 }
+for _,interval in ipairs(intervals) do
+  local i = integrator:new(ks)
+  sample(2.0, interval, function() i:update() end)
+  i:input(kz)
+  sample(0.5, interval, function() i:update() end)
+  print(string.format("sampling interval: %f, %5d updates over 2.5s total = %.15f", interval, i.nup, i:output()))
+end