How to draw a mathmatical function?

[smilie]

Dear peoples,

how can i draw a mathematical functions?
I want to draw y=x²/4 and i need to set some drillings depending of this function.

Any ideas?

[wmayer]

Check out this link. Since arbitrary parametric curves are not supported this solution does an approximation with line segments (simple) or B-spline curves.

viewtopic.php?f=13&t=6226#p50611

[shoogen]

I want to draw y=x²/4

Our geometry kernel support parabolas, so there should be no need to use an approximation
http://opencascade.sourcearchive.com/do ... abola.html
the default Parabola seems to have the right scaling and position, but is symetrical to the x-axis.

Code: Select all

import FreeCAD
import Part
p=Part.Parabola
#p.Focal=1.0
p.rotate(FreeCAD.Placement(FreeCAD.Vector(),FreeCAD.Rotation(90,0,0)))

But haven't figured out yet, how to add limits.

[jmaustpc]

Hyperbola is there as well.

[wmayer]

Our geometry kernel support parabolas, so there should be no need to use an approximation

The parabolas are handled the geometric way so that converting the algebraic form y=x²/4 is not that easy. Besides that when using a B-Spline curve of degree two then it's not an approximation but 100% exact.

[shoogen]

Our geometry kernel support parabolas, so there should be no need to use an approximation

The parabolas are handled the geometric way so that converting the algebraic form y=x²/4 is not that easy.

Why? I thought that i just need to set XDir to (0,1,0), YDir(1,0,0) and i would change Axis to (0,0,-1) to keep orientation right handed. The focal length (F) defaults to 1.0

Code: Select all

The Geom_Parabola parabola is parameterized as follows:
P(U) = O + U*U/(4.*F)*XDir + U*YDir 

Besides that when using a B-Spline curve of degree two then it's not an approximation but 100% exact.

That is true for parabolas, but not for the hyperbolas jmaustpc mentioned in the meantime. And getting the 100% exact B-Spline representation is not obivous to me. (I wouldn't trust the OCCT interpolation functions on this).