How can I plot a line on a plane?

6 次查看（过去 30 天）
MJ
MJ 2021-5-6
回答： DGM 2021-5-6
If I have a plane in this following format z = f(x,y) = a + b*x + c*y + d*x^2 + e*x*y + f*y^2 and I have a line in y=f(x) = p1*x^2 + p2*x + p3 format, how can I plot the line on the plane?
For example, if I use hold on to try to plot the two together, the f(x) line gets plotted two-dimensionally flat in z = 0 plane. Instead of the z = 0 plane I would like a specific plane of z = a + b*x + c*y + d*x^2 + e*x*y + f*y^2 format.
It would be better if I could somehow combine the two equations and turn it into a 3D line and only plot that if possible.

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2021-5-6
Ran in:
C = randi([-9 9], 1, 9);
a = C(1), b = C(2), c = C(3), d = C(4), e = C(5), f = C(6), p1 = C(7), p2 = C(8), p3 = C(9)
a = 2
b = -6
c = 5
d = 1
e = -7
f = -9
p1 = 5
p2 = -2
p3 = -5
syms x y
z = a + b*x + c*y + d*x^2 + e*x*y + f*y^2
z = 
y1 = p1*x^2 + p2*x + p3
y1 = 
y2 = solve(z == y1, y)
y2 = 
z21 = simplify(subs(z, y, y2(1)))
z21 = 
z22 = simplify(subs(z, y, y2(2)))
z22 = 
fsurf(z, [-10 10], 'edgecolor', 'none');
hold on
fplot3(x, y2(1), z21, [-10 10])
fplot3(x, y2(2), z22, [-10 10])
hold off

更多回答（1 个）

DGM
DGM 2021-5-6
There are probably a bunch of ways to do this, but I did this:
% plot range
xrange = [-5 5];
yrange = [-5 5];
% I choose to use parameter vectors
a = [1 1 1 1 1 1];
p = [1 1 1]
syms x y
% a surface
z1 = a(1) + a(2)*x + a(3)*y + a(4)*x.^2 + a(5)*x.*y + a(6)*y.^2
% a curve in the x-y plane
y1 = p(1)*x.^2 + p(2)*x + p(3)
% the projection of y1 on z1
z2 = subs(z1,y,y1)
% curve extends beyond plot range, so find the parameter limits for fplot3
% if it extends beyond other edges, you'll have to solve for that too
curvelimits = double(solve(y1==5,x))'; % limiting values of x
h1 = fsurf(z1,[xrange yrange],'edgecolor','none'); hold on
fplot3(x,y1,z2,curvelimits,'linewidth',3)
fplot(x,y1,curvelimits)

类别

在 Help Center 和 File Exchange 中查找有关 Surface and Mesh Plots 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by