LOGO-L> Re: 3-d mesh & sombrero curve

[George Mills <mills@softronix.com>]

With a .5 step you get
the following attachment.

MHELHEFNY@FRCU.EUN.EG wrote:
> 
> ;Helo George Mills
> ;Here is the true "sombrero" surface as described in the old "matlab"
> ;manual; it is a surface that everybody likes to show.
> ;The surface has the simple equation z=sin(r)/r where r=sqrt(x^2+Y^2)
> ;for pupose of semilarity I used y=sin(r)/r where r=sqrt(x^2+z^2).
> ;this curve like the previous one of electric charges in space use the
> ;the mesh concept. of course many of the surfaces of revolution which
> ;was programed by rolling a curve thro' 360 degrees;could be drawn
> ;on a mesh.I shall try posting the code of one of these curves soon.
> ;Hopping that you will enjoy it.
> ;Mhelhefni
> ;---------------------------------------------------------------
> to go
> turnon3d cs ;ht
> make "step first questionbox [input step bet.(.5  - 2)][]
> grid 14 :step
> end
> 
> to grid :r :step
> gridx :r :step gridz :r :step
> end
> 
> to gridx :r :step
> pu
> for [x -:r :r :step][for [z -:r :r :step][make "xsq :x* :x make "zsq :z* :z
> make "r sqrt(:xsq+ :zsq) +.001
> make "f (sin :r*180/pi)/ :r
> setxyz :x*15 :f*200 :z*15] pu setz -zcor pd]
> pu
> end
> 
> to gridz :r :step
> pu
> for [z -:r :r :step][for [x -:r :r :step][make "xsq :x* :x make "zsq :z* :z
> make "r sqrt(:xsq+ :zsq) +.001
> make "f (sin :r*180/pi)/ :r make "a
> setxyz :x*15 :f*200 :z*15] pu setx -xcor pd]
> end
> 
> to turnon3d
> ; This is a library procedure for 3-d
> perspective
> setturtle -1
> setxyz 800 1000 800
> setturtle 0
> end
> ;-----------------------------------------------------------------

-- 
===============================================================
George Mills
email: mills@softronix.com
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