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# Challenge

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## Challenge

 Back in the 60's, as a young engineer, I played with Optimisation using Hill Climbing.  I had a robust hill climbing program, written in Fortran, and a weird curved hill function to test it on. Over the years the program has been translated into Delphi and Prolog for searching in N dimensions It is now time to shoe-horn it into OpenScad!!! THE CHALLENGE I have mislaid my old test function, so have created a flying saucer shape to test my routine as it is built.  The shape is a bit too simple for my liking – can you come up with a bigger challenge? N=2 is fine! //----------------------------------------------------------------------------------------------------- // UFO for hill climbing test R=10;       // radius of dome A=80;       // angle of cone from vertical // cone continues to infinity, but our UFO goes to disc radius D D=50; // height of cone H = (D-R)/tan(A); H = (D-R)/tan(A); \$fn=100; sphere(r=R); translate([0,0,-H])cylinder(r1=D,r2=R,h=H); //-------------------------------------------------------------------- // function to calculate the Z for X,Y of UFO function ZZ(X,Y) =   let(XY=sqrt(X*X+Y*Y))     XY
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## Re: Challenge

 What sort of hill climbing algorithm are you talking about?  (The term "hill climbing" appears to be very vague, apparently referring to any algorithm that tries to maximize by going "up" at each step...or maybe even not that if you count "stochastic hill climbing".)   My challenge function for a maximization algorithm that doesn't use 2nd order approximation: f = function(x,y) 100-(x*x+y*y/50); starting your optimization on the x or y axis is cheating.  (You can rotate the function to a random angle so that you can't find the "easy" starting points if you must.)  How many iterations to get 6 digits of accuracy? GregL wrote Back in the 60's, as a young engineer, I played with Optimisation using Hill Climbing.  I had a robust hill climbing program, written in Fortran, and a weird curved hill function to test it on. Over the years the program has been translated into Delphi and Prolog for searching in N dimensions It is now time to shoe-horn it into OpenScad!!! THE CHALLENGE I have mislaid my old test function, so have created a flying saucer shape to test my routine as it is built.  The shape is a bit too simple for my liking – can you come up with a bigger challenge? N=2 is fine! //----------------------------------------------------------------------------------------------------- // UFO for hill climbing test R=10;       // radius of dome A=80;       // angle of cone from vertical // cone continues to infinity, but our UFO goes to disc radius D D=50; // height of cone H = (D-R)/tan(A); H = (D-R)/tan(A); \$fn=100; sphere(r=R); translate([0,0,-H])cylinder(r1=D,r2=R,h=H); //-------------------------------------------------------------------- // function to calculate the Z for X,Y of UFO function ZZ(X,Y) =   let(XY=sqrt(X*X+Y*Y))     XYdiscuss-leave@.openscad Sent from the OpenSCAD mailing list archive at Nabble.com._______________________________________________ OpenSCAD mailing list To unsubscribe send an email to [hidden email]
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## Re: Challenge

 adrianv wrote GregL wrote > I have mislaid my old test function, so have created a flying saucer shape > to test my routine as it is built.  The shape is a bit too simple for my > liking – can you come up with a bigger challenge? Romulan Battle Bagel?? Sent from the OpenSCAD mailing list archive at Nabble.com._______________________________________________ OpenSCAD mailing list To unsubscribe send an email to [hidden email]
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## Re: Challenge

 On Friday 21 May 2021 20:19:42 cbernhardt wrote: > adrianv wrote > > > GregL wrote > > > >> I have mislaid my old test function, so have created a flying > >> saucer shape > >> to test my routine as it is built.  The shape is a bit too simple > >> for my liking – can you come up with a bigger challenge? > > Romulan Battle Bagel?? > > > Chuckle, but needs more phaser ports? > > > -- > Sent from: http://forum.openscad.org/Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty:  soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable.  - Louis D. Brandeis Genes Web page _______________________________________________ OpenSCAD mailing list To unsubscribe send an email to [hidden email]
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## Re: Challenge

 Gene Heskett wrote Chuckle, but needs more phaser ports? Sent from the OpenSCAD mailing list archive at Nabble.com._______________________________________________ OpenSCAD mailing list To unsubscribe send an email to [hidden email]
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## Re: Challenge

 On Saturday 22 May 2021 07:59:53 cbernhardt wrote: > Gene Heskett wrote > > > Chuckle, but needs more phaser ports? > > > Thats more like it. ;-) > > > -- > Sent from: http://forum.openscad.org/Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty:  soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable.  - Louis D. Brandeis Genes Web page _______________________________________________ OpenSCAD mailing list To unsubscribe send an email to [hidden email]