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Math Bug?
Posted: Wed Sep 12, 2012 1:49 am
by spacebuddy
I have this equation and it always returns 0, not sure if I am doing something wrong.
Answer=(3000/4000) * 20
always returns 0, on my calculator I get 15
I tried this in another language and it also returns 15
Can someone verify this?
Using the latest beta (2) of PB
Re: Math Bug?
Posted: Wed Sep 12, 2012 2:17 am
by STARGÅTE
3000 and 4000 are integers!
So 3000/4000 is 0!
0 * 20 = 0
If 3000/4000 sould be 0.75 you have to use floats:
Answer = (3000.0/4000) * 20
Re: Math Bug?
Posted: Wed Sep 12, 2012 2:19 am
by IdeasVacuum
Not a bug, just syntax. It's written in integers. Try this:
Code: Select all
Answer = (3000.00/4000.00) * 20.00
Debug Answer
For an accurate divide value it's best to doubles. Also, best not to mix integers with doubles, even though the above would be fine with 20 instead of 20.00.
Re: Math Bug?
Posted: Wed Sep 12, 2012 2:22 am
by Demivec
If 'Answer' is not a float then you will get '0' for the answer because it is using integer arithmetic. This is because (3000/4000) is less then 1 and so it is truncated to zero before multiplying it by 20.
If you insist on using an integer type of variable (i.e. byte, word, long, etc.) to hold the result you can rearrange the equation to multiply first and divide last:
Code: Select all
answer = (3000 / 4000) * 20 ; = 0
Debug answer
answer = 20 * 3000 / 4000 ; = 15
Debug answer
Re: Math Bug?
Posted: Wed Sep 12, 2012 2:33 am
by spacebuddy
Thanks for all the replies, now I understand and it works find
