fixed points in the plots
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Hi,
I have a program that includes a graph of functions in 3D
I need to fix points on the drawing (show the location of the points on the drawing),
I used
hold on ;
plot (A(1),B(2.1),G(3.021),'r*')
plot (A(0.0001),B(3),G(3.21),'r*')
plot (A(3.654),B(3.1),G(2.15),'r*')
But an error appeared to me...
Error in POINTS (line 45)
plot (A(1),B(2.1),G(3.021),'r*')
if any Prof. can help me ...thanks alot
采纳的回答
Walter Roberson
2021-4-11
syms A B G
A, B, and G are created as scalar symbols
f = matlabFunction(sum1m2, 'vars', [A, B, G]);
g = matlabFunction(sum3m4, 'vars', [A, B, G]);
h = matlabFunction(sum5m6, 'vars', [A, B, G]);
f, g, and h are created as numeric functions of three inputs.
plot (A(1),B(2.1),G(3.021),'r*')
plot (A(0.0001),B(3),G(3.21),'r*')
plot (A(3.654),B(3.1),G(2.15),'r*')
You try to index scalar A at 1, which works, giving you back the scalar symbol A .
You try to index scalar B at 2.1, which fails, because you cannot index at non-integers... and if you could do that, you would be indexing past the end of the scalar.
You try to index scalar G at 3.021, which fails, non integer, past the end of the scalar. Is it possible that function g was intended? But function g needs three parameters, not one.
I suspect what you want is
plot ((1),(2.1),(3.021),'r*')
plot ((0.0001),(3),(3.21),'r*')
plot ((3.654),(3.1),(2.15),'r*')
10 个评论
hasan s
2021-4-12
hasan s
2021-4-17
Walter Roberson
2021-4-17
It works for me. If I take your code and remove the
plot (A(1),B(2.1),G(3.021),'r*')
plot (A(0.0001),B(3),G(3.21),'r*')
plot (A(3.654),B(3.1),G(2.15),'r*')
which we already know to be wrong, and if we put in
plot3(1,2,3,'r*')
then you can see a red star in the graph.
You have "hold on" in effect, and your xlim, ylim, and zlim are all [0 4], so if you were to try to draw at points outside that range, then they would not be in view. For example if you wanted to plot at 4.1 3.1 2.1 then it would be off the screen. If that happens you can use
xlim auto; ylim auto; zlim auto
Walter Roberson
2021-4-17
NumPoints = 50;
tic
digits(16);
syms A B G
N = 100;
Q1 = rand(10,N);
Q = vpa(reshape(Q1,1,[]));
sum1=0;sum2=0;sum3=0;sum4=0;sum5=0;sum6=0;
for j=1:1000
sum1=sum1+1/(A+(G*B*((Q(j))^(G-1))));
sum2=sum2+(Q(j));
sum3=sum3+(G*((Q(j))^(G-1)))/(A+(G*B*((Q(j))^(G-1))));
sum4=sum4+(Q(j))^(G);
sum5=sum5+(((G*log(Q(j)))*((Q(j))^(G-1)))+((Q(j))^(G-1)))/(A+(B*G*((Q(j))^(G-1))));
sum6=sum6+((Q(j))^(G))*log(Q(j));
end
sum1m2 = vpa(sum1 - sum2);
sum3m4 = vpa(sum3 - sum4);
sum5m6 = vpa(B*sum5-B*sum6);
f = matlabFunction(sum1m2, 'vars', [A, B, G]);
g = matlabFunction(sum3m4, 'vars', [A, B, G]);
h = matlabFunction(sum5m6, 'vars', [A, B, G]);
[Ag, Bg, Gg] = meshgrid(linspace(0, 4,NumPoints));
Fgrid = f(Ag,Bg,Gg);
Ggrid = g(Ag,Bg,Gg);
Hgrid = h(Ag,Bg,Gg);
grids = {Fgrid, Ggrid, Hgrid};
gridnames = {'f', 'g', 'h'};
ngrid = length(grids);
cmap = parula(ngrid);
view(3);
patches = gobjects(1,ngrid);
surfaces = cell(ngrid, 1);
for K = 1 : ngrid
surfaces{K} = isosurface(Ag, Bg, Gg, grids{K}, 0);
patches(K) = patch(surfaces{K}, 'facecolor', cmap(K,:), 'edgecolor','none','FaceAlpha', 0.5, 'displayname', gridnames{K});
end
xlabel('A');
ylabel('B');
zlabel('G');
legend show
hold on ;
plot3((1),(2.1),(3.021),'r*')
plot3((0.0001),(3),(3.21),'r*')
plot3((3.654),(3.1),(2.15),'r*')
hold off
toc
hasan s
2021-4-17
Walter Roberson
2021-4-17
You did not ask for that.
points = [
1, 2.1, 3.021;
0.0001, 3, 3.21;
3.654, 3.1, 2.15;
]
scatter3(points(:,1), points(:,2), points(:,3), 'r*');
for K = 1 : size(points,1)
text(points(K,1), points(K,2), points(K,3), sprintf('A=%g B=%g G=%g', points(K,:)));
end
hasan s
2021-4-17
Walter Roberson
2021-4-17
There are also datatips(), but datatips() automatically move to the closest data point, which I did not think you would want to do.
hasan s
2021-4-18
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