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Unitless?

57 REPLIES 57
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Message 1 of 58
Anonymous
857 Views, 57 Replies

Unitless?

Unit definitions cause (me at least) a lot of modeling problems. They arise when I really need to illegally mix units but I don't know why that should be so. For instance, if I want to make a coil's number of revolutions or some angle dependant on a dimension, it seems to be written in petrified dung somewhere that it's a no no. If a value is unitless, why would it care if it was multiplied by a dimension? A dimension value is a number and a unitless value is a number, no? So what gives? Been trying to figure that is for a long time without a clue. Anyone able to explain that, maybe and will this be true forever (Forever's 3 years. ... Evidence: my first wife said she was going to stay with me forever)? ~Larry
57 REPLIES 57
Message 41 of 58
Anonymous
in reply to: Anonymous

Heh, heh. My true grasp of math shows thru. My statement wasn't pointed at anyone in particular, I'm just in agreement with Larry. No offense. -- Dave Hoder Product Design Engineer idX Seattle www.idxcorporation.com "Keith Panik" wrote in message news:4092a33f$1_3@newsprd01... "My time is better spent figuring out how to build things from napkin sketches than reveling in my grasp of calculus." Ahhh, spoken like a true tech. I was just trying to offer some help. By the way this is far from calculus. kp "Dave Hoder" wrote in message news:40929fe8$1_3@newsprd01... Me too. Just because I don't have an engineering degree doesn't mean I can't help to manufacture $100m worth of product a year. My time is better spent figuring out how to build things from napkin sketches than reveling in my grasp of calculus. -- Dave 'both barrels' Hoder Product Design Engineer idX Seattle www.idxcorporation.com "Larry Caldwell" wrote in message news:40927703_2@newsprd01... I'm just a ol'hick designer, not an Engineer
Message 42 of 58
Anonymous
in reply to: Anonymous

Dave's post (answer) that won't show in NNTP due to the heavy HTML coding - -- Anne Brown Discussion Groups Administrator Autodesk, Inc. From: "Dave Hoder" Newsgroups: autodesk.inventor.8 References: <40914937$1_1@newsprd01> <40928274$1_3@newsprd01> Subject: Re: Unitless? Date: Fri, 30 Apr 2004 11:45:22 -0700 Lines: 85 Organization: idX Seattle MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01C42EA8.A172DF60" X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Message-ID: <40929ec8_3@newsprd01> X-Trace: newsprd01 1083350728 66.224.99.34 (30 Apr 2004 18:45:28 GMT) Path: newsprd01!not-for-mail Xref: newsprd01 autodesk.inventor.8:19294 This is a multi-part message in MIME format. ------=_NextPart_000_000D_01C42EA8.A172DF60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable --=20 Dave Hoder Product Design Engineer idX Seattle www.idxcorporation.com "Kevin Wehner" wrote in message = news:40928274$1_3@newsprd01... >If IV is going to correctly add or multiply a mix of milimeters and = inches, it has to know how the units relate to get a final number.=20 Mixing inches & millimeters should be an easy calculation requiring no = input on the users part (except adding the suffix). The value returned = should be in what ever units are set as standard & should be able to be = changed by the user. >If IV is expecting 'in' and gets 'hp' it won't have an established = relationship between the two to give you the correct value. In which case, a simple dialog box "Choose which value to consider = unitless" would fix the problem. ------=_NextPart_000_000D_01C42EA8.A172DF60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 

--
Dave Hoder
Product Design Engineer
idX = Seattle
www.idxcorporation.com
"Kevin Wehner" <kevinwehner @ zoominternet . net> wrote in = message=20 news:40928274$1_3@newsprd01...
>If IV is going to correctly add = or multiply a=20 mix of milimeters and inches, it has to know how the units relate to = get a=20 final number.
 
Mixing inches & millimeters = should be an easy=20 calculation requiring no input on the users part (except adding the = suffix).=20 The value returned should be in what ever units are set as standard=20 & should be able to be changed by the user.
 
>If IV is expecting 'in' and gets = 'hp' it=20 won't have an established relationship between the two to give = you the=20 correct value.
 
In which case, a simple dialog box = "Choose which=20 value to consider unitless" would fix the problem.
 
------=_NextPart_000_000D_01C42EA8.A172DF60--
Message 43 of 58
xavierl
in reply to: Anonymous

Catia also has an equation editor....only problem is its 10 times as complicated.
regards
Frans X Liebenberg
Message 44 of 58
Anonymous
in reply to: Anonymous

The fun one sounds like something I might have written, eh? Thanks Keith, got a new favorites now just for that topic. ~Larry "Keith Panik" wrote in message news:40927a0e$1_1@newsprd01... Here's a fun one: http://www.chemistrycoach.com/use.htm Here is an informative one: http://en.wikipedia.org/wiki/Dimensional_analysis Here is another: http://physics.about.com/library/weekly/aa021503a.htm This should keep you busy for awhile. kp "Larry Caldwell" wrote in message news:40927703_2@newsprd01... I'm just a ol'hick designer, not an Engineer, but thanks ... I'll do that. Haven't seen any good sites, have ya'? ~Larry "Keith Panik" wrote in message news:4092486a$1_3@newsprd01... Larry, what this all boils down to is "dimensional analysis", which is one of the first things learned as an engineering student. If you are not fimilliar with this I think it would help to spend a little time looking this up on the internet. I think it will clear things up for you a bit. kp "Larry Caldwell" wrote in message news:40919991$1_1@newsprd01... Yeah ... I gotcha. In algebra class there were several, er, um, farer distractions shall we say, and while I have done that a bit, I never got very good at it. Wasn't much way to know if an equation was canceled correctly or not without the answers in the back of the book or someone to say. Wonder if there are any sites these days that give you feedback on such things. Thanks again Patrick! ~Larry "Patrick Berry" wrote in message news:40919391$1_1@newsprd01... I think the key here is that IV is designed around metric units. When using non-metric units they are automatically converted to metric internally. Just like in algebra, the units need to be treated like scalar values and must cancel out correctly to balance the equations. Patrick
Message 45 of 58
Anonymous
in reply to: Anonymous

I understand that Kevin, but actually the thrust of my comment was about the possibility of having a unit that actually mean unitless and would subsequently be available to use with any other type unit and not worry about it because, in that case, the unit (unitless or maybe a new one actuallyunitless) would be totally irrelevant; it would be treated as any other untagged number/integer/whatever used to easily get the results I'm trying to achieve even without knowing the ins and outs of Dimensional Analysis. ... To be used in calculator mode I guess. ~Larry "Kevin Wehner" wrote in message news:40928274$1_3@newsprd01... I may not understand why you are having a problem. If IV is going to correctly add or multiply a mix of milimeters and inches, it has to know how the units relate to get a final number. If IV is expecting 'in' and gets 'hp' it won't have an established relationship between the two to give you the correct value. "Larry Caldwell" wrote in message news:40914937$1_1@newsprd01... Unit definitions cause (me at least) a lot of modeling problems. They arise when I really need to illegally mix units but I don't know why that should be so. For instance, if I want to make a coil's number of revolutions or some angle dependant on a dimension, it seems to be written in petrified dung somewhere that it's a no no. If a value is unitless, why would it care if it was multiplied by a dimension? A dimension value is a number and a unitless value is a number, no? So what gives? Been trying to figure that is for a long time without a clue. Anyone able to explain that, maybe and will this be true forever (Forever's 3 years. ... Evidence: my first wife said she was going to stay with me forever)? ~Larry
Message 46 of 58
Anonymous
in reply to: Anonymous

"fxlxd" wrote... > Catia also has an equation editor....only > problem is its 10 times as complicated. ooh, not good 8~) Thanks, Frans. ================================
Message 47 of 58
rllthomas
in reply to: Anonymous

I guess I'm a little lost. Clearly you want IV to assume any number you type in is a length with the units of whatever the defaults are since this is what the majority of numbers you type in are. When you want to increase a unit of length by a multiple you merely add a suffix of ul. I'm just surprised the Underwriters Labratories hasn't tried to make them change that. Kind of like how Design Elements are iFeatures now 🙂

I always used units when I used Mathcad so IV seems pretty straight forward to me. Besides, if the units work out doesn't that mean you have the right solution? LOL
Message 48 of 58
Anonymous
in reply to: Anonymous

How this started was not being able to use an inch*unitless entry in the coil command dialog or inch*deg to drive an angle with a particular dimension. Otherwise the units are fine and work great. The only place they give me fits are in the two above scenarios ... even though, it's most likely I don't fully understand all the relevant principals, I'd guess. ~Larry "rllthomas" wrote in message news:20249682.1083603388362.JavaMail.jive@jiveforum2.autodesk.com... > I guess I'm a little lost. Clearly you want IV to assume any number you type in is a length with the units of whatever the defaults are since this is what the majority of numbers you type in are. When you want to increase a unit of length by a multiple you merely add a suffix of ul. I'm just surprised the Underwriters Labratories hasn't tried to make them change that. Kind of like how Design Elements are iFeatures now :) > > I always used units when I used Mathcad so IV seems pretty straight forward to me. Besides, if the units work out doesn't that mean you have the right solution? LOL
Message 49 of 58
Anonymous
in reply to: Anonymous

Unitless even a real word? ~Larry "rllthomas" wrote in message news:20249682.1083603388362.JavaMail.jive@jiveforum2.autodesk.com... > I guess I'm a little lost. Clearly you want IV to assume any number you type in is a length with the units of whatever the defaults are since this is what the majority of numbers you type in are. When you want to increase a unit of length by a multiple you merely add a suffix of ul. I'm just surprised the Underwriters Labratories hasn't tried to make them change that. Kind of like how Design Elements are iFeatures now :) > > I always used units when I used Mathcad so IV seems pretty straight forward to me. Besides, if the units work out doesn't that mean you have the right solution? LOL
Message 50 of 58
Anonymous
in reply to: Anonymous

It might help if, when expressing unitless values, you think of them as having no existance except as the quotient of two like unit values; i.e. if you input "5" Revolutions for a coil feature you are entering the quotient of 1800 Degrees of revolution / 360 Degrees of revolution, entering "5" as the number of pattern instances = number of copied instances = total Distance / interval Distance, etc. Then, again, it might not help at all.... 8~) (btw, the majority of usenet news groups don't support or allow binary attachements.) ======================= "Larry Caldwell" wrote in message news:40968f00$1_3@newsprd01... > How this started was not being able to use an inch*unitless > entry in the coil command dialog or inch*deg to drive an > angle with a particular dimension. Otherwise the units are > fine and work great. The only place they give me fits are > in the two above scenarios ... even though, it's most > likely I don't fully understand all the relevant principals, > I'd guess. > ~Larry
Message 51 of 58
Anonymous
in reply to: Anonymous

..... and, just in case you've never investigated it, you can declare compound units: in deg, deg / in, in / deg, etc. Sometimes making the formal declarations and working with them can help keep things sorted out. ========================
Message 52 of 58
Anonymous
in reply to: Anonymous

Thanks Jeff, I can also go back to the one you sent me awhile back that has a pattern on an arc and updates with the dims then go through that one again. Haven't gotten back to it yet. It's always: "...after I get done with...". ~Larry "Jeff Howard" wrote in message news:4097d831_1@newsprd01... > .... and, just in case you've never investigated it, you can declare > compound units: in deg, deg / in, in / deg, etc. Sometimes making the > formal declarations and working with them can help keep things sorted out. > > ======================== > >
Message 53 of 58
Anonymous
in reply to: Anonymous

Need to find a wholesale distibutor for round tuits? 8~) ================= . "Larry Caldwell" wrote... > ...... It's always: "...after I get done with...".
Message 54 of 58
gnrnr
in reply to: Anonymous

One of the guys here at work has a round tuit on the back of his business cards.

Very amusing

Steve
Message 55 of 58
A_Fantucci
in reply to: Anonymous

Goodmorning

 

I'm Alessandro F. new in this Forum.

 

I've a problem with unitless parameter.

 

Imy standard and my model parameters is in "mm" but when insert a personal parameters "Unitless" linked ti model parameter in "mm" return a value 10 times small:

ex:

L_bar (mm)=1890mm

test (Unitless)=189

 

unitless_problem_AlessandroF.PNG

 

how can set the value of "Unitless" equal my "mm" parameter?

 

many Thanks

ALessandro

Message 56 of 58
JDMather
in reply to: Anonymous

You have replied to a thread that is 10 yrs old.

 

You can assign the units. 

Attach your file here.


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Message 57 of 58
mrattray
in reply to: A_Fantucci

Simply click in the field that says unit-less and change it to mm.
The unit-less unit converts to cm by default, but this isn't a real conversion. Unit-less is meant for things that don't make sense to have a unit, like constants.
Mike (not Matt) Rattray

Message 58 of 58
A_Fantucci
in reply to: mrattray

thank you

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