Hi Alec,

Thanks for your reply...

I used maple for solving that set of equations. Because eventually I had to differentiate the sub-condition g ( which was in this case x^3+y^3+z^3-a^3=0),as it indeed is a Langrange Multipliers problem...which made it easier to substitute all the critical points the solve command gave me...

Think I'll use the commando aswell now ... I was just practicing the method, as I'll have to write at least SOMETHING down on the exam ;)

Thx again.

Thank you, it gave me a better view on how loops work, although I don't think a loop is able to give me what I need/want. p1:=display(seq(plot3d([a*cos(i-x),a*sin(i-x),3*x],a=8..20,x=0..12),i=0..6,0.05),insequence=true): This is a part of a 3d object, and the problem is that I need to be able to have a 3rd parameter, I'll call it "n". the object is circular, and adding changing the (i-x) to (((n-1)(2*Pi)/n)+i-x) rotates the object by 2*Pi/n compared to the original object. I want to be able to give n a certain value, so it adapts automatically in the function. F.ex if I set n = 3 it should create 3 objects, that are rotated by (2*Pi)/3 and (4*Pi)/3. And I should be able to adapt it very easily every time. So I actually need a parameter. Koen

ah, thank you, I see. At this point I solved it by using i/6,and multiplying the i range by 6. But it might be better to use a step to keep the commando's clean. The screw is quite complete now, all I'd like to do is to use a certain number of parameters to easily adapt the screw. there is one parameter that I do not really know how to handle it. screw:=[seq(plot3d([a*cos((2*Pi/n)+x),a*sin((2*Pi)/n+x),3*x],a=8..20,x=0..12,numpoints=1000,orientation=[i,60]),i=-36..36)]: As you can see I added (2*Pi)/n with n as the number of blades. So for example, I'd like to have, if I set the number of blades to 3 or 4 that it creates 4 functions with n ranging from 1 in the first function, and 4 in the fourth function. And all 4 should appear in the display. Do you know if this is possible? Koen

Thanks again Looks like I missed it. But I have another, let's call it, something I'd like to solve, although it's not really of a problem. > restart:with(plots): > screw:=[seq(plot3d([a*cos(x),a*sin(x),3*x],a=-20..20,x=1..4*Pi,numpoints=1500,orientation=[i,60]),i=-30..30)]: > tube:=[seq(implicitplot3d([x^2+y^2=40,z],x=-15..15,y=-15..15,z=1..12*Pi,color=green,orientation=[i,60]),i=-30..30)]: > g:=[seq(sphere([15*cos(i),15*sin(i),3*i],1),i=1..13)]: > p3:=display(g,insequence=true): > p1:=display(tube,insequence=true): > p2:=display(screw,insequence=true): > display(p1,p2,p3); This is what I have now, although I've got the problem that the ball is already on top when about 25% of the complete animation is done, is there a way that I can let the i-value rise 0.5 per frame? Koen

Thanks It works, but when I try to add the central cilinder using the following lines, it doesn't work. >tube:=[seq(implicitplot3d([x^2+y^2=40,z],x=-15..15,y=-15..15,z=1..12*Pi,numpoints=1500,orientation=[i,60]),i=-180..180)]: >display(screw,tube,insequence=true) I get an error about interrupted computation. Is it possible to display 2 animated objects? Koen