Delta-time running average

Results: http://imgur.com/a/m9Tv7
[        15][                    .\scripts\index-cmd\init.lua:                        @ 266]	entered interactive mode
[        15]Interactive input. Call "exit()" to continue
[        16]
[        16]>> function gauss()
[      7993] function >> local x = 0
[      8742] function >> for i = 1, 16 do
[      9532] function | do >> x = x + math.random()
[     10712] function | do >> end
[     10712] function >> return (x - 8) / 4
[     10712] function >> end
[     10712] >> function lerp(a, b, wa, wb)
[     24429] function >> return (a * wa + b * wb) / (wa + wb)
[     41682] function >> end
[     44535]>> function frametime()
[     62414] function >> if math.random() < 0.1 then
[     75593] function | if >> return gauss() * 10 + 100
[    109930] function | if >> else
[    111429] function | if >> return gauss() * 2 + 20
[    118363] function | if >> end
[    122392] function >> end
[    123550]>> time_acc = 0
[    152000]>> function update(ft)
[    162633] function >> time_acc = ft
[    168302] function >> end
[    169181]>> require('img', _ENV)
[    201024]table: 0x005241c8
[    395579]>> function runtest(accfunc, filename)
[    398319] function >> local fm = fmat:spawn(200, 1000, 3)
[    398870] function >> for y = 999, 0, -1 do
[    401272] function | do >> local ft = frametime()
[    405077] function | do >> local aval = accfunc(ft)
[    417648] function | do >> local x = math.floor(aval)
[    431332] function | do >> for i = 0, x < 200 and x or 199 do
[    472999] function | do | do >> fm.data[y][i][0] = 1
[    523713] function | do | do >> fm.data[y][i][1] = 0
[    564106] function | do | do >> fm.data[y][i][2] = 0
[    566360] function | do | do >> end
[    567958] function | do >> for i = x >= 0 and x+1 or 0, 199 do
[    591111] function | do | do >> fm.data[y][i][0] = 1
[    595119] function | do | do >> fm.data[y][i][1] = 1
[    597522] function | do | do >> fm.data[y][i][2] = 1
[    600528] function | do | do >> end
[    602065] function | do >> if ft >= 0 and ft < 200 then
[    621790] function | do | if >> local x = math.floor(ft)
[    636714] function | do | if >> fm.data[y][x][0] = 0
[    647258] function | do | if >> fm.data[y][x][1] = 0
[    652011] function | do | if >> fm.data[y][x][2] = 0
[    653983] function | do | if >> end
[    656006] function | do >> end
[    668996] function >> export{filename, fm}
[    707303] function >> end
[    709714]>> function acc_immediate(ft)
[    732712] function >> return ft
[    736639] function >> end
[    737472]>> runtest(acc_immediate, 'acc_immediate.png')
[    760409]
[    760409]>> function acc_lerp(ft)
[    810445] function >> time_acc = lerp(time_acc, ft, 1, 1)
[    830930] function >> end
[    833288]>> runtest(acc_lerp, 'acc_lerp.png')
[    843593][string "function runtest(accfunc, filename)..."]:6: bad argument #1 to 'floor' (number expected, got nil)
[    843594]stack traceback:
[    843594]	[C]: in function 'floor'
[    843594]	[string "function runtest(accfunc, filename)..."]:6: in function 'runtest'
[    843594]	[string "print(runtest(acc_lerp, 'acc_lerp.png'))"]:1: in main chunk
[    843594]	[C]: in function 'pcall'
[    843594]	.\scripts\index-cmd\init.lua:281: in function <.\scripts\index-cmd\init.lua:265>
[    843595]	[C]: in function 'pcall'
[    843595]	.\scripts\system\boot.lua:43: in main chunk
[    843595]>> function acc_lerp(ft)
[    853364] function >> time_acc = lerp(time_acc, ft, 1, 1)
[    854704] function >> return time_acc
[    859971] function >> end
[    860683]>> runtest(acc_lerp, 'acc_lerp.png')
[    863464]
[    863464]>> function acc_lerp(ft)
[    967367] function >> time_acc = lerp(time_acc, ft, 50, 1)
[    977870] function >> return time_acc
[    981987] function >> end
[    982857]>> runtest(acc_lerp, 'acc_lerp50.png')
[    986987]
[    986988]>> function acc_square(ft)
[   1047712] function >> local a = 0.5*ft
[   1061325] function >> time_acc = lerp(time_acc, ft, 1-a, a)
[   1081268] function >> end
[   1083695]>> runtest(acc_square, 'acc_square_0.5.png')
[   1101627][string "function runtest(accfunc, filename)..."]:6: bad argument #1 to 'floor' (number expected, got nil)
[   1101627]stack traceback:
[   1101627]	[C]: in function 'floor'
[   1101627]	[string "function runtest(accfunc, filename)..."]:6: in function 'runtest'
[   1101628]	[string "print(runtest(acc_square, 'acc_square_0.5.png'))"]:1: in main chunk
[   1101629]	[C]: in function 'pcall'
[   1101629]	.\scripts\index-cmd\init.lua:281: in function <.\scripts\index-cmd\init.lua:265>
[   1101630]	[C]: in function 'pcall'
[   1101630]	.\scripts\system\boot.lua:43: in main chunk
[   1101631]>> function acc_square(ft)
[   1106668] function >> local a = 0.5*ft
[   1107259] function >> time_acc = lerp(time_acc, ft, 1-a, a)
[   1108145] function >> return time_acc
[   1111700] function >> end
[   1112608]>> runtest(acc_square, 'acc_square_0.5.png')
[   1116459]
[   1116460]>> function acc_square(ft)
[   1156238] function >> local a = 0.01*ft
[   1162289] function >> time_acc = lerp(time_acc, ft, 1-a, a)
[   1165269] function >> return time_acc
[   1166379] function >> end
[   1167207]>> runtest(acc_square, 'acc_square_0.01.png')
[   1171427]
[   1171428]>> function acc_square(ft)
[   1224123] function >> local a = 0.001*ft
[   1237238] function >> time_acc = lerp(time_acc, ft, 1-a, a)
[   1239605] function >> return time_acc
[   1240798] function >> end
[   1241562]>> runtest(acc_square, 'acc_square_0.001.png')
[   1244498]
[   1244498]>> function acc_exp(ft)
[   1283627] function >> time_acc = ft + (time_acc - ft)*math.exp(-0.1*ft)
[   1327042] function >> return time_acc
[   1330723] function >> end
[   1331768]>> runtest(acc_exp, 'acc_exp_0.1.png')
[   1350443]
[   1350443]>> time_acc = 0
[   1367843]>> runtest(acc_square, 'acc_square_0.001.png')
[   1372082]
[   1372082]>> time_acc = 0
[   1403843]>> runtest(acc_exp, 'acc_exp_0.1.png')
[   1406081]
[   1406082]>> function acc_exp(ft)
[   1446955] function >> time_acc = time_acc + (ft - time_acc)*math.exp(-0.1*ft)
[   1461688] function >> return time_acc
[   1465879] function >> end
[   1466440]>> time_acc = 0
[   1468291]>>
[   1468403]
[   1468404]>> runtest(acc_exp, 'acc_exp_0.1.png')
[   1471156]
[   1471156]>> function acc_exp(ft)
[   1516448] function >> time_acc = time_acc + (ft - time_acc)*math.exp(-0.01*ft)
[   1526901] function >> return time_acc
[   1530501] function >> end
[   1531019]>> time_acc = 0
[   1531579]>> runtest(acc_exp, 'acc_exp_0.01.png')
[   1535224]
[   1535224]>> function acc_exp(ft)
[   1558146] function >> time_acc = ft + (time_acc - ft)*math.exp(-0.01*ft)
[   1561575] function >> return time_acc
[   1567102] function >> end
[   1567912]>> time_acc = 0
[   1569031]>> runtest(acc_exp, 'acc_expi_0.01.png')
[   1576103]
[   1576104]>> function acc_expd(ft)
[   1610898] function >> d = time_acc - ft
[   1636562] function >> time_acc = ft + d*math.exp(-0.1*d)
[   1653326] function >> return time_acc
[   1656381] function >> end
[   1656997]>> time_acc = 0
[   1662689]>> runtest(acc_expd, 'acc_expd_0.1.png')
[   1669296]
[   1669296]>> function acc_expd(ft)
[   1691308] function >> local d = time_acc - ft
[   1703818] function >> time_acc = ft + d*math.exp(-0.1*math.abs(d))
[   1716577] function >> return time_acc
[   1719890] function >> end
[   1720769]>> time_acc = 0
[   1725360]>> runtest(acc_expd, 'acc_expd_0.1.png')
[   1728982]
[   1728983]>> function acc_expd(ft)
[   1770496] function >> d = time_acc - ft
[   1772085] function >> time_acc = ft + d*math.exp(-1*d)
[   1775850] function >> return time_acc
[   1779841] function >> end
[   1780394]>> time_acc = 0
[   1780903]>> runtest(acc_expd, 'acc_expd_1.png')
[   1783831]
[   1783832]>> function acc_expd(ft)
[   1801881] function >> d = time_acc - ft
[   1802734] function >> time_acc = ft + d*math.exp(-1*math.abs(d))
[   1807868] function >> return time_acc
[   1812253] function >> end
[   1812884]>> time_acc = 0
[   1813726]>> runtest(acc_expd, 'acc_expd_1.png')
[   1815251]
[   1815251]>> function acc_expd(ft)
[   1876129] function >> d = time_acc - ft
[   1876963] function >> time_acc = ft + d*math.exp(-10*math.abs(d))
[   1886973] function >> return time_acc
[   1889907] function >> end
[   1890157]>> time_acc = 0
[   1890479]>> runtest(acc_expd, 'acc_expd_10.png')
[   1893348]
[   1893349]>> function acc_expd(ft)
[   1911882] function >> d = time_acc - ft
[   1913507] function >> time_acc = ft + d*math.exp(-0.01*math.abs(d))
[   1923628] function >> return time_acc
[   1926782] function >> end
[   1927346]>> time_acc = 0
[   1928173]>> runtest(acc_expd, 'acc_expd_0.01.png')
[   1932206]
[   1932206]>> exit()
[   2099953]
[   2099953][                    .\scripts\index-cmd\init.lua:                        @ 297]	exited from interactive mode