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formulas of curve
Roland Schwarz Aug 4, 2008 12:27 PM (in response to Selcuk Bolukbasi)A series of tangent arcs can not be described with a single formula due to discontinuities. It would require a set of discontinuous formulae.
formulas of curve
Ricky Gutierrez Aug 4, 2008 12:42 PM (in response to Roland Schwarz)i have seen a friend of mine take points off a series of discontinuous arcs from "MATLAB" and create an array.
Once those points are found you can easily import them to solidworks via a design table creating points then use Spline to connect them.
It is not exact but the standard deviation is minimal depending on how accurate you need the curve to be. It is lots of work to do especially if your curve doesn't need to be exact.
Im sure someone else can provide easier alternatives.


formulas of curve
Selcuk Bolukbasi Aug 4, 2008 2:48 PM (in response to Selcuk Bolukbasi)Roland Schwarz and Ricky Gutierrez thanks for interest,
i will wait another ideas,
and that compound curve is continuous curve (not discontinuous)
formulas of curve
Jerry Steiger Aug 5, 2008 4:08 AM (in response to Selcuk Bolukbasi)Selcuk,
I'm not sure if this is of any help to you, but SW has a function called a "Fit Spline" that fits a single spline to a any geometry that you choose. You can control the accuracy of the fit spline. It's in Tools/Spline Tools.


formulas of curve
Mahir Abrahim Aug 4, 2008 3:28 PM (in response to Selcuk Bolukbasi)I've written macros to go from formula to curve, but curve to formula is more complicated. Like Roland pointed out, you can't describe a series of tangent arcs with only one equation. It is indeed discontinuous in that your curve is given by a series of separate circular equations that share continuous slope (1st derivative), but discontinuous 2nd derivative. However, you can use one formula to describe a spline that approximates those arcs. After forming your arcs, try going over it with a spline that is close to the same shape. After that, extract the XY coordinates of the spline's control points. You might be able to find or write a macro that does this automatically. Using the coordinates of the control points and the TREND() function in Excel (or whatever other software you have available) you can calculate a regression for those known coordinates. If you use Excel, you will have to fit to a function of the form y = m1*x1 + m2*x2 + ... + b, where m1, m2, m3 correspond to x, x^2, x^3 as used in a spline's polynomial equation. 
formulas of curve
Mahir Abrahim Aug 5, 2008 5:45 AM (in response to Selcuk Bolukbasi)Hmm... didn't know about that one, Jerry. Thanks. 
formulas of curve
Selcuk Bolukbasi Aug 5, 2008 7:39 AM (in response to Selcuk Bolukbasi)dear friends thanks all of you i wanna give more information about that question;
but i cant send any file;
can anybody help me to send a file to explain what i want;

formulas of curve
Jerry Steiger Aug 6, 2008 9:27 PM (in response to Selcuk Bolukbasi)Selcuk,
You have to zip the file before you can attach it. The process to attach a file is tedious. It seems like you have to click a number of buttons to get it done. As I recall, you have to upload the file and then you have to attach it.
formulas of curve
Christopher Thompson Aug 7, 2008 12:21 AM (in response to Jerry Steiger)I would like to see SolidWorks provide a curvedriven equation feature as it already exists in ProE, and it would be helpful if SW added this to SW 2009. I believe other SW users have been requesting this feature for a few years.
In ProE, datum points from excel can be imported, than a curve can be routed through these points in the X, Y, and Z directions. I assume SolidWorks can do this as well, but I have not tested it. Perhaps the 3D Curve allows the creation of a spline through 3D datum points.
formulas of curve
Mahir Abrahim Aug 7, 2008 3:10 AM (in response to Christopher Thompson)Chris, SW is taking baby steps towards the equation driven curve feature. SW2009 has the ability to create 2D splines of the form y=f(x). It's nowhere near as flexible as ProE's equation driven curves, but at least it's getting there. If you're looking for similar 3D curve functionality now, you can try this thread. 
formulas of curve
Eddie Cyganik Oct 2, 2008 5:25 PM (in response to Christopher Thompson)
Chris,
You're referring to "TrajPar" (Trajectory Parameters?)
Yes I have asked and I have complained and I have touted the fact that Pro/E had this capability from DayOne, so what's the problem?
Got Me!!!
formulas of curve
Selcuk Bolukbasi Oct 9, 2008 6:55 AM (in response to Eddie Cyganik)Charles, i send file (you want to obtain formulas or equation)
thanks for interest
formulas_of_curve.zip 22.4 KB






formulas of curve
Selcuk Bolukbasi Aug 7, 2008 8:04 AM (in response to Selcuk Bolukbasi)Jerry can you tell me how can i send a zip file as a reply please. i m new user of this forums so please write step one step please if you want to help me;
thanks for everything to everyone
sorry may be this isnt related our question but i have to learn to give more clue in our question and answer
formulas of curve
Mahir Abrahim Aug 7, 2008 2:45 PM (in response to Selcuk Bolukbasi)1. Click the Attach File(s) button at the bottom of the Reply window.
2. In the Attach File(s) window that comes up, click the Choose button and select the file you want to upload (zip, png, jpg).
3. Click Upload File.
4. Now select that file in the file listing and click the green Attach File link.


formulas of curve
Selcuk Bolukbasi Aug 8, 2008 5:01 AM (in response to Selcuk Bolukbasi)thanks Mahir Abrahim i understood that i use quick reply so i dont see attach button thanks for interest
formulas of curve
Charles Culp Oct 1, 2008 6:28 PM (in response to Selcuk Bolukbasi)You can email me the file, if you wish, and I will post it for you.


formulas of curve
Selcuk Bolukbasi Oct 1, 2008 6:37 PM (in response to Selcuk Bolukbasi)thanks for interest charles, now we are in ramadan holiday so i dont have that curve we will start 0n monday. i can send on monday.

formulas of curve
18MMYCK Oct 9, 2008 2:22 PM (in response to Selcuk Bolukbasi)as others said, you cant get mathematical formulas out of the software, automatically. for the case you have posted, it's easy to obtain the equation manually. if you need the equation of this curve only, i can help. 
formulas of curve
Selcuk Bolukbasi Oct 10, 2008 6:56 AM (in response to Selcuk Bolukbasi)tim, i only need that compound curve equation (formulas) such as y= ax4+bx3+cx2+dx+e . sure starting point is 0,0 it means that e=0
thanks for interest

formulas of curve
Selcuk Bolukbasi Oct 10, 2008 6:58 AM (in response to Selcuk Bolukbasi)tim and also can you explain how can i obtain that formulas;
i will be soo happy thanks

formulas of curve
18MMYCK Oct 10, 2008 1:01 PM (in response to Selcuk Bolukbasi)as the curve is compound, the equation is compound too. see below. is this what you are looking for?


formulas of curve
Mahir Abrahim Oct 10, 2008 5:39 PM (in response to Selcuk Bolukbasi)Tim, you go above and beyond. I like being helpful, but I don't think I'd go as far as doing someone's algebra homework for them 
formulas of curve
Mahir Abrahim Oct 10, 2008 5:40 PM (in response to Selcuk Bolukbasi)Tim,
By the way, what is your avatar? It looks like some Persian flag. 
formulas of curve
18MMYCK Oct 10, 2008 7:14 PM (in response to Selcuk Bolukbasi)yeah thats a persian symbol called Farvahar, which dates back to thousands of years ago. i've seen that in bistoon, http://i16.tinypic.com/4q51pvr.jpg http://www.izadmehr.com/bistoon.katibe.jpg the symbol is carved on a mountain 70m above ground (700 BC) and in persepolis,takht jamshid (515 BC). http://www.bestirantravel.com/...s/shiraz/p_symbol.jpg
formulas of curve
Phil Marra Oct 11, 2008 10:16 AM (in response to 18MMYCK)Does anyone know if its possible to create a curve from an aspheric equation?


formulas of curve
Selcuk Bolukbasi Oct 14, 2008 6:16 AM (in response to Selcuk Bolukbasi)tim;
firstly thanks for interest and answer,
but i need only one equation so we changed (fit) that single curves as coumpound curve and we obtain a curve called spline,
now i have to learn that spline equation 
formulas of curve
18MMYCK Oct 14, 2008 11:42 AM (in response to Selcuk Bolukbasi)well, you have to search the web to find the general equation of splines. the equation depends on several factors such as selection of degree, knots and spline points, knot weights, and other stuff which i really don't remember now.
that's an interesting problem (for a student).