Inertia Matters !!

Hello,

I got a few question about these inertia in grasshopper.

If you look at the picture below i got a section and have the inertias in grasshopper at the right corner.

And also you can see the inertia at the rhino window which gives me more detailed (longer digits).

For this section i have to be able to read 5 digits in the Lx and 6 digits in the Ly.However, grasshopper prefers to give me the euler constant method which reduces the digits of Ly to 5.

So how can i make the grasshopper indicate the full number of inertia or to control the digits of a floating numbers by myself like at a normal number slider ?

Replies to This Discussion

Permalink Reply by David Rutten on November 30, 2014 at 2:55pm

"Euler constant method"? Do you mean scientific notation?

If you want to see (on the screen) more digits, you'll have to format the number yourself. However the actual value contains more digits than you can see, so if you only use the number as part of further calculations, then it should already work to the highest possible level of accuracy Rhino provides.

The attached file shows some examples of custom formatting. The area is formatted to different decimal places, and also using different cultures (note the comma in the Turkish format). The inertia including the errors are formatted using a more advanced pattern that includes both fixed decimals, scientific notation and multiple lines.

Attachments:

formatting.gh, 10 KB

Permalink Reply by Bora Doker on November 30, 2014 at 4:34pm

Yes the scientific notation (e+...)

ah thank you for your interesting solution.. Yes it can be easy to understand the area format but what about the culture. What does it refer to exactly in this computing ?

For the inertia moments i really didnt understand the inertia (error) part could you explain it a bit more. Does it has to have an inertial error at all time and then use those in the formatting ??

Permalink Reply by David Rutten on November 30, 2014 at 5:20pm

Different languages (or "cultures") have different rules for formatting numbers, currencies, dates and times. They also have different rules regarding upper and lower casing and how different characters are sorted. By default Grasshopper uses either the English/American or the Invariant culture. However certain components allow you to override this with a culture of your choosing.

The only visible difference here is that the comma is used as the decimal separator instead of the period.

When Rhino calculates things like length, area, moments etc. it's often an approximation of the real value. Sometimes this approximation is as accurate as possible given 64-bit floating point numbers. Sometimes the approximation is less accurate, for example when additional iterations no longer result in a significant improvement, or when a mesh is used as a proxy for a nurbs surface.

Calculations such as Area, Volume, Moments of Inertia are not totally accurate, however we know the maximum error that can be expected. So if the moment of inertia around x is 156.7856 ± 0.02, it can be anything between 156.7656 and 156.8056.

Permalink Reply by Bora Doker on December 1, 2014 at 3:39am

Oh i see now. But still need to get use to this format writing technique though.. Its not looks too easy when you first see this, but got the idea.. :)

Thanks for your great support for now !

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