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Piet Hein’s super elipse

Zaki

Member
Hy Guys


I need to draw a Piet Hein's super ellipse. Actual equation is |x/a|^r+|y/b|^r = 1,


its perametric is x=a cos^2/rt, y=b sin^2/r t.


the value of r is 5/2 according to shape I required


the problem is that I couldnt successfully put this equation into WF3. I had tried a lot but not succesfull. What I put is


a=8.25, b=8, c=5/2, d=2/c


in curve equation


x=a*((cos(t*360))^d) y=b*((sin(t*360))^d), z=0.


Please guide me where I am wrong, I couldnt understand.


Zaki
Edited by: Zaki
 
/* For cartesian coordinate system, enter parametric equation
/* in terms of t (which will vary from 0 to 1) for x, y and z
/* For example: for a circle in x-y plane, centered at origin
/* and radius = 4, the parametric equations will be:
/*&amp ; ;nbs p; x = 4 * cos ( t * 360 )
/*&amp ; ;nbs p; y = 4 * sin ( t * 360 )
/*&amp ; ;nbs p; z = 0
/*---------------------------------------------------------- ---------
x=8.25*(cos(90*t))^.2
y=8*(sin(90*t))^.2
z=0

That will give you 1 quadrant, you can mirror to get the others


Edited by: dr_gallup
 
Thanx a lot dear Dr


would you like to tell me what wrong with my formula?? I think its abs value that calculate all -ve values as positive, isnt it?? where 0.2 comes from?? it couldnt be 0.8?? as 2/(5/2) = 0.8


anyway, thanks a lot
 
Opps, I just did the exponent calc in my head, thought the 2 canceled out and it was 1/5. Just change the .2 to .8

I think if you try to evaluate more than the 1st quadrant (0-90 degrees) then you have negative values raised to a fractional power. This gives a complex number as the result and Pro/E gives you this error message:

Invalid data type combination at right side of expression

In your format, this works:
a=8.25
b=8
c=5/2
d=2/c

x=a*((cos(t*90))^d)
y=b*((sin(t*90))^d)
z=0
 
You r rite Dr.


I was thinking that how could we put an abs value for both x and y. as you can see in geniune equation, It is a must to calculate every x or y value to +ve. first quadrant solve this matter I had finish my project. Thanx a lot dear


Zaki
 

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