Legend Producing Wrong Colour Lines

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Alyssa Neale
Alyssa Neale 2022-7-29
编辑： VBBV 2022-7-29
Hi I have been trying to plot multiple lines on the same plot and the colours of the lines are coming up incorrectly. Here is my code and the results. I am currently running 2020b
plot(x,freal,'k')
hold on
plot(x,ftaylor0,'r')
plot(x,ftaylor1,'b')
plot(x,ftaylor2,'g')
plot(x,ftaylor3,'m')
plot(x,ftaylor4,'c')
hold off
legend('f(x)', 'p0(x)', 'p1(x)', 'p2(x)', 'p3(x)', 'p4(x)')
xlabel('x')
ylabel('f(x)')
  2 个评论
VBBV
VBBV 2022-7-29
can you provide the full code ?
Alyssa Neale
Alyssa Neale 2022-7-29
x=-5:0.1:5;
freal=x.*exp(-x);
ftaylor0= 1/exp(1);
ftaylor1= 1/exp(1);
ftaylor2= (1/exp(1))-(1/(2*exp(1)).*(x-1).^2);
ftaylor3= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3);
ftaylor4= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3)-((1./(8.*exp(1))).*(x-1).^4);

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回答（1 个）

VBBV
VBBV 2022-7-29
Ran in:
x=-5:0.1:5;
freal=x.*exp(-x);
ftaylor0= 1./exp(x); % they is scalar in your code
ftaylor1= 1./exp(-x); % this is scalar in your code
ftaylor2= (1/exp(1))-(1/(2*exp(1)).*(x-1).^2);
ftaylor3= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3);
ftaylor4= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3)-((1./(8.*exp(1))).*(x-1).^4);
plot(x,freal,'k')
hold on
plot(x,ftaylor0,'r')
plot(x,ftaylor1,'b')
plot(x,ftaylor2,'g')
plot(x,ftaylor3,'m')
plot(x,ftaylor4,'c')
hold off
legend('f(x)', 'p0(x)', 'p1(x)', 'p2(x)', 'p3(x)', 'p4(x)')
You can see ftaylor0 and ftaylor1 are scalars with just one point. You need to make them vectors
  1 个评论
VBBV
VBBV 2022-7-29
编辑：VBBV 2022-7-29
Ran in:
x=-5:0.1:5;
freal=x.*exp(-x);
ftaylor0= 1./exp(1) % they is scalar in your code
ftaylor0 = 0.3679
ftaylor1= 1./exp(1) % this is scalar in your code
ftaylor1 = 0.3679
ftaylor2= (1/exp(1))-(1/(2*exp(1)).*(x-1).^2);
ftaylor3= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3);
ftaylor4= (1/exp(1))-(1./(2.*exp(1)).*(x-1).^2)+((1./(3.*exp(1))).*(x-1).^3)-((1./(8.*exp(1))).*(x-1).^4);
plot(x,freal,'k')
hold on
plot(ftaylor0,'>r','MarkerSize',10) % use a marker to plot
plot(ftaylor1,'sb','MarkerSize',4) % use a marker to plot
plot(x,ftaylor2,'g')
plot(x,ftaylor3,'m')
plot(x,ftaylor4,'c')
hold off
legend('f(x)', 'p0(x)', 'p1(x)', 'p2(x)', 'p3(x)', 'p4(x)','location','best')
You can also plot them as data point with proper legend

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