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Plotting the area defin
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Iluating x & y, I don't want a & b to be always the same as long as 0<=a<=1 & 0<=b<=1. But I have no idea to resolve this issue!!
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Answers (3)
John D'Errico
on 13 Oct 2018
You know how to use meshgrid! In fact, I know that, because you used it in your other question.
So it you want to plot something over all combinations of a and b, then why not use meshgrid? (10000 points in each dimensions will be wild overkill of course.)
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John D'Errico
on 13 Oct 2018
Edited: John D'Errico
on 13 Oct 2018
As I said, you resolve the issue by using meshgrid. meshgrid generates ALL combinations of the two variables, a & b.
[a,b] = meshgrid(0:.01:1,0:.01:1);
So a and b are now TWO dimensional arrays, here, each of size 101x101. Now compute x and y as directed.
x = a.^2 - b.^2;
y = a.*b;
plot(x,y,'.')
The result is a sort of triangular domain, with curved edges along the top.
Are you asking how to generate the boundary of that domain? From what you have said, I don't think so.
edgeind = convhull(x(:),y(:));
plot(x(edgeind),y(edgeind),'r-')
But you need to understand that when you want to generate all combinations of two variables like this, USE MESHGRID.
Bruno Luong
on 13 Oct 2018
Edited: Bruno Luong
on 13 Oct 2018
almost right, you need to make a & b oriented in 2 different dimensions (here row for a and column for b)
a=linspace(0,1,101);
b=linspace(0,1,101)'; % <= make a column
x=a.^2-b.^2;
y=a.*b;
plot(x,y,'.b');
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Bruno Luong
on 13 Oct 2018
Edited: Bruno Luong
on 13 Oct 2018
??? x, y are already computed from all combination of a, b with resolutions of 0.01.
So what your question is about? Might be your should slow down think, then ask a real question.
Bruno Luong
on 13 Oct 2018
Or perhaps you want this?
a=linspace(0,1,100)';
b=linspace(0,1,100)';
rect = [a 0+0*a;
1+0*b b;
flip(a) 1+0*a;
0+0*b flip(b)];
a = rect(:,1);
b = rect(:,2);
x=a.^2-b.^2;
y=a.*b;
plot(x,y,'-b');
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