inline calculator

[MikeJarosz]

I have been aware that Revit allows inline calculation for a while, but have never really exploited the possibilities. Wherever a number can be input, entering a formula like =3*3 will be interpreted by Revit as 9.

My question is, what functions are available (such as square root) and what math symbols are used? Are parentheses allowed? I searched F1-help for "calculator" and got pages and pages about engineering calcs, but nothing about =2+2! I assume arithmetic symbols like +-*/ will work, which are pretty standard in modern software.

For the math people out there I like the idea of entering =8/3 rather than 2.666666666666666666667. I'm assuming that Revit has some rigorous routines for arithmetic calculation in both decimal and binary that will result in more accuracy. Years ago I had a discussion with Irwin Jungweis about numbers, until it went over my head. But I learned that a repeating number is not neccessarily irrational. 2.6666666667 is rational, whereas 3.14159 is not. That's why I think 8/3 is a good input number.

[CADastrophe]

You can use parenthese in the inline formulas, and you can use functions like "=sqrt( x )".

Using exponents is a little trickier, because of the units. You can't just input "=2' ^ 2 " because Revit will interprit that as an area (ft * ft = ft²) which is invalid for a linear input, hence an "Inconsistent Units" error.
For an exponential value, inputting "=(2 ^ 2) * 1' " would yield the proper results.


The decimal system we have is not perfect. I've always liked this little tidbit below:

1/3 + 1/3 + 1/3 = 1
______ _
1/3 = 0.3
_ _ _ _ _ _ ___ _ _ _
0.3 + 0.3 + 0.3 = 0.9, which does NOT equal 1

[MikeJarosz]

I notice parentheses require spaces. Your tidbit, to the best of my knowledge is a problem that exists in every number system. The repeating number 1/3 has its equivalent in the binary representation of 1/10. I think it was the Intel 386 processor that actually had a bug built into its circuits that could not calculate binary 1/10. They had to issue a massive recall.

Thinking about it, not too many readers here will remember the 386....

[CADastrophe]

I notice parentheses require spaces.

No, you don't actually need the spaces. I placed them in my examples because I'm just used to doing that to provide more clarity when typing out formulas in posts. Sorry.

[jeffh]

These 2 links to the wikihelp might be of use.

http://wikihelp.autodesk.com/Revit/enu/2012/Help/Revit_User's_Guide/2654-Tools_an2654/2894-Formulas2894/2897-Valid_Fo2897

http://wikihelp.autodesk.com/Revit/enu/Community/Tips_and_Tricks/Families%2c_Parameters%2c_Formulas/Formulas_for_%22Everyday%22_Use

[MikeJarosz]

Jeff:

Thanks! Just what I was looking for.