topic Re: function f(x) in AutoCAD Forum

function f(x)

yakaic — Tue, 31 Oct 2023 11:04:43 GMT

Hi,

Is there a way creating a line that shows a function like "f(x)=x²"? Optimal case is that I can set the start point e.g. at x=-3 and the end point at x=3 so I get the function in that area.

Is there anything like this?

Thanks for help.

Aaron

Re: function f(x)

tramber — Tue, 31 Oct 2023 13:02:37 GMT

You can make a lisp or create a script pleased to Excel to send a spline.

The only thing is to determinate how many points you want 😉

The more you draw, the more precise you are.

Re: function f(x)

TheCADnoob — Tue, 31 Oct 2023 13:15:29 GMT

Check out this article about using Excel to create functions and then pasted in AutoCAD.

https://forums.autodesk.com/t5/autodesk-community-voices/autocad-excel-your-design-with-a-graphing-cad-culator/ba-p/11868735

Re: function f(x)

tramber — Tue, 31 Oct 2023 13:21:56 GMT

(defun c:fun1(/ *osmode* inter a b dis) (setq inter 25 a -3 b 3 dis(/(- b a)(float inter))) (setq *osmode*(getvar"osmode")) (setvar"osmode"0) (command "_pline"(list a (* a a))) (repeat inter(command(list(setq a(+ a dis))(* a a)))) (command) (setvar"osmode"*osmode*) )

You can easily change inter, a and b.

Load that and run FUN1

Re: function f(x)

leeminardi — Tue, 31 Oct 2023 15:16:03 GMT

@TheCADnoob The link is a nice write up but the command parameters should specify fit points not not control vertices since the explicit function for sine is used.

That is, spline m f 0,0 not spline m cv 0,0

Also, when choosing the delta x value for something like a trig function it would be better if the minimum and maximum values were explicitly specified.

As a side note, the attached Excel file includes a custom function I wrote for creating of B-splines from control vertices. It will duplicate the splines created in AutoCAD if the weights of vertices are all 1.0 (a B-spline and not a NURBS). The worksheet compares the accuracy of a degree 3 B-spline (AutoCAD spline) for 180°with a true sine curve. Macros must be enabled for the Excel file to use the custom Excel BSPLINE function.

Re: function f(x)

Kent1Cooper — Tue, 31 Oct 2023 15:42:55 GMT

Perhaps >this topic< may be of interest to you.

Re: function f(x)

TheCADnoob — Tue, 31 Oct 2023 18:05:58 GMT

fantastic points