problem with dot product

Replies to This Discussion

Permalink Reply by Massimiliano Trave on April 23, 2012 at 6:56am

Permalink Reply by Danny Boyes on April 23, 2012 at 7:02am

It is zero when I opened it.

Permalink Reply by Massimiliano Trave on April 23, 2012 at 7:20am

the problem remains,  maybe  the cause is some setting of rhino?really i don't understand ...

Please help me

Permalink Reply by Giulio Piacentino on April 23, 2012 at 7:33am

-1.0057e-15 is zero within 10^-14, or 0.00000000000001 units, tolerance, which means you could consider this 0. You have to always consider tolerance with this type of calculations. This is computation with double-precision floating point arithmetics.

Thanks,

- Giulio
________________
giulio@mcneel.com

Permalink Reply by Danny Boyes on April 23, 2012 at 7:33am

-1.0057e-15 is the scientific notation for the number 0.0000000000000010057.

It's safe to say that it is 0. The discrepancy is cause by rounding errors in the calculation when using floating point numbers. You can read more about accuracy issues here

Permalink Reply by Massimiliano Trave on April 23, 2012 at 7:40am

giulio and Danny thanks so much,I had forgotten this type of problem.