OpenEuphoria

Re: [EuForum] Definition of insanity...

• Posted by Pete Lomax <petelomax at blueyonder.co.uk> Nov 24, 2004
• 555 views

On Tue, 23 Nov 2004 14:14:41 -0800, CoJaBo <guest at RapidEuphoria.com>
wrote:

>You must never have done this:
>}}}
<eucode>
>for o=1 to rand(1000000)*100 do
>	--It doesnt seem to happen
>	--unless the program runs for a while
>end for
>integer g
>g=time()*100
>?g
>include get.e
>?wait_key()
></eucode>
{{{

>Run it a few times, you'll eventually get a fairly unexpected error!
>This was the cause of headaches for many weeks before I figured it out...

I assume you mean that:
	g=floor(time()*100)

is occasionally (and seemingly against the docs) required?

If so, and having run the above several times, I'm slightly confused.
Compare this to:

if 0.1+0.2!=0.3 then
	puts(1,"not equal!\n")
end if

Which fails (100%) because (eg) 0.1 cannot be *exactly* represented in
binary floating point (a hardware thing, not a dig at RDS). What
confuses me is your code does not fail very often...

Try this (failed 2dp atoms shown on the right, apologies for the line
wrap):

procedure t100(sequence a)
integer i
	for j=1 to length(a) do
		i=a[j]*100
		?i
	end for
end procedure
t100({1.90,1.91,1.92,1.93,1.94,1.95,1.96,1.97,1.98,1.99,	-- <none>
	  2.00,2.00,2.02,2.02,2.04,2.04,2.06,2.06,2.08,2.09,	--2.01,
2.03, 2.05, 2.07
	  2.10,2.11,2.12,2.13,2.14,2.15,2.16,2.17,2.17,2.19,	--2.18,
	  2.21,2.21,2.21,2.23,2.23,2.25,2.25,2.27,2.27,2.29,	--2.20,
2.21, 2.24, 2.25, 2.28
	  2.29,2.29,2.29,2.29,2.34,2.34,2.36,2.36,2.38,2.38,	--2.30,
2.31, 2.32, 2.33, 2.35, 2.37, 2.39
	  2.40,2.40,2.42,2.42,2.44,2.44,2.46,2.46,2.48,2.48,	--2.41,
2.42, 2.45, 2.47, 2.48
	  2.50,2.50,2.52,2.52,2.54,2.54,2.56,2.57,2.58,2.59,	--2.51,
2.53, 2.55
	  2.60,2.61,2.62,2.63,2.64,2.65,2.66,2.67,2.68,2.69,	-- <none>
	  2.70,2.71,2.72,2.73,2.74,2.75,2.76,2.77,2.78,2.79})	-- <none>

I am *NOT* saying this can be fixed (apart from use of floor()),
I am just exploring this in detail.
It's a fairly strange spread, if anything can be read into that...
Does anyone regularly using another language get the same results?

Yours curiously,
Pete