Two more bug with MaplePrimes:

1. When one edits a post with an uploaded plot (probably other uploads also), the plot disappears.
2. The plot of a user's reputation over time doesn't work: The area where the plot use to be is just blank.

@adel-00 To do that, you need to remove the definition of tau from the initialization section. Only give tau a value before each individual plot.

tau:= Pi:
P1:= plot(Spec, -15..15, options )
 
Normalize:= proc(P::specfunc(anything, PLOT))
local A,Smax1;
     A:= op([1,1], P);
     Smax1:= max(A[..,2]);
     if A::list then  A:= Matrix(A)  end if;
     A[..,2]:= A[..,2]/Smax1;
     subsop([1,1]= A, P)
end proc:

P1:= Normalize(P1):
tau:= 2*Pi:
P2:= plot(Spec, -15..15):
P2:= plottools:-translate(Normalize(P2), 0, 1):
tau:= Pi/3:
P3:= plot(Spec, -15..15);
P3:= plottools:-translate(Normalize(P3), 0, 2):
display([P1,P2,P3]);

@Kitonum The English plural of a noun that ends in -sis is to change -sis to -ses, and this is pronounced with a long e: -seez. So, the plural of basis is bases, pronounced BAY-SEEZ. Sorry to have a language with such arbitrary-seeming rules.

@ecterrab Now that I know that it is expected to be idempotent, I will post them when I encounter them. I haven't saved my examples because I didn't think that it would be considered a bug. The idempotency should be mentioned on the help page.

@yendis Okay, you specify a line and a plane in any form that you want, and I'll show you how to use geom3d on them.

That was asked and answered two weeks ago: here's the link

@nm Your questions are very good, but I do not have the answers. I do use some trial-and-error. I have a good feeling for what expand, combine, and evalc do. But when I use one-argument simplify or convert(..., form) (where form is a function name or function class name), then I am using trial-and-error. One thing that makes one-argument simplify hard to understand is that it is not idempotent, i.e., simplify(simplify(expr)) is not necessarily the same as simplify(expr).

The reason that I did not answer in the other thread is that I think that what you ultimately want is a procedure that determines whether a line segment intersects a triangle. This idea about the end point of the line segment satisfying 2 or 3 of the inequalities is not enough for that.

@adel-00 From your previous posts, I am guessing that you simply want the original plot shifted up by 1. So, suppose that P is the original plot. Then use

P2:= plottools:-translate(P, 0, 1);
plots:-display([P,P2]);

@nm You are computing the (partial) derivatives of f with respect to x. What is wanted is the derivatives of y with respect to x, also known as the implicit derivatives.

@nm Numeric integration shows that 1/2/I/Pi is correct.

@nm Your specs are almost identical to mine except that I am using Windows 8. I doubt that that could account for the difference. I don't understand it, but I'll try playing with it some more.

Show me the result of the following: After the above, give the command op(rhs(%)).

@Hayno So, we have the line segment L joining the origin and some other point that we're calling the vector. Let's call the triangle T. Determing which of these is the goal:

1. whether L intersects T?
2. whether L lies completely inside T?
3. whether the terminal point of L lies inside T?

2 and 3 are easy. 1 seems harder than just determing whether a line intersects the triangle.

@Hayno That doesn't make sense to me. What does it mean for a vector to intersect something? Give me a specific example of a vector intersecting something simple, like a square; and an example where the vector does not intersect the square. A vector is not a line, nor does it determine a specific line.

I am making this Reply primarily to promote your Question to the top of the Active stack, because I think that it is a good question and I hope that it gets seen. This is by far the most active day that I've ever seen on MaplePrimes, and the Active stack is getting pushed out of the immediately visible range (the top seven) every few hours.

In the meantime, read the help pages ?plots,surfdata and ?plots,listplot3d . These commands are the key to turning 3d point data into a surface plot.