Thread Subject:

Problem with machine precision

Hello,

I have a problem with the machine presion namely if I calculate 1+cosd(120) +cosd(240) than the result in Matlab is 5.5511e-017 instead of zero. This gives me a lot of problems later in my program. Why is this not equal to zero?

Thanks

Steven

Well Hermano, this is due to the representation of floating points in the computer. To learn more about this you can read this link:
http://www.mathworks.com/support/solutions/en/data/1-16FOQ/

actually you should program your code differently in state of using
if (a-b = 0)
you can use for example
if(a-b<eps)
or so

hope it helps
Walid

"Hermano Cappa" wrote in message <j1tim1$njb$1@newscl01ah.mathworks.com>...
> Hello,
>
> I have a problem with the machine presion namely if I calculate 1+cosd(120) +cosd(240) than the result in Matlab is 5.5511e-017 instead of zero. This gives me a lot of problems later in my program. Why is this not equal to zero?
>
> Thanks
>
> Steven