40 lines
1.3 KiB
Lua
40 lines
1.3 KiB
Lua
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
|