math.floor issue?

[cristip]

for(var i =0, j=0; i < 15; i++)
{
j += .2;
trace("Math.floor("+j+") = " + Math.floor(j))
}

outputs:

...
Math.floor(1.6) = 1
Math.floor(1.8) = 1
Math.floor(2) = 1
Math.floor(2.2) = 2
Math.floor(2.4) = 2
...

can somebody tell me why Math.floor(2) = 1 ?

[devonair]

hey, cristip,

it's because of the way Flash handles fractional numbers.. Drag your code out to 100 instead of 15 and you'll see that you wind up with numbers like 32.7999999999999 (rather than 32.8).. So, really your 2 is 1.9999999999999.. I forget why it does this, but there are other threads dealing with it, if you're in the mood for searching..

d.

[cristip]

well if so why when i trace

trace("Math.floor("+j+") = " + Math.floor(j))

the first j is 2 and the second is 1.9999999... ?

I've run searches.. but no result.. does anyone knows a topic that discuss the same problem?

Thank you

[devonair]

http://www.macromedia.com/cfusion/knowledgebase/index.cfm?id=tn_13989

[sneeuwitje]

As long as you work with integers there's no issue. Following adaption to your code is beating around the bush quite a bit, but will perform as expected ;):for(var i =0, j=0; i < 150; i += 10)
{
j += 2;
trace("Math.floor("+j/10+") = " + Math.floor(j/10))
}
output:...
Math.floor(1.8) = 1
Math.floor(2) = 2
Math.floor(2.2) = 2
...

[sneeuwitje]

or easier:for (var i=0, j=0; i<15; i++, j=i*0.2)
{
trace("Math.floor("+j+") = " + Math.floor(j))
}
If you get it, I get it :confused:

[cristip]

http://www.macromedia.com/cfusion/knowledgebase/index.cfm?id=tn_13989

:) Thank you!