testing function execution speed?

Questions
1

How can I test the execution speed of a function (or part of the code)?

I tried a couple ways along the lines of the snippet below (including elapsedtime and timediff() ), but I keep getting zero as a result.

startTime = os.time()
     function()
print(os.time()-startTime)
2

Put it in a loop that runs it 100000 times (or more, until it takes a few sec to complete)

3

ElapsedTime gives you fractions of a second, but only updates from one frame to the next, so put the million loop in the draw function (with a flag so that it only fires once).

4

os.time should be all right in setup, the problem was he only ran it once

5

Yeah, os.time would work just in setup, though it’s whole seconds only. I guess it depends how accurate you need to be/ how much time you mind waiting. What I find interesting, is that often the values you get vary quite a lot, even though the exact same set of instructions are being run.

6

@Kirl Here’s an example of how I time things. You’ll have to change the loop value depending on what you time.

function setup()
    loop=10000000
    s=os.clock()
    for z=1,loop do
        a=math.sin(z)
        a=math.cos(z)
        a=math.log(z)
        a=math.sqrt(z)
    end
    print(os.clock()-s)
end
7

@yojimbo2000 - I guess the iPad could be doing other things in the background, like updating apps or polling for mail.

8

Thanks guys!