MATLAB: How to plot with 3 matrix

Question

Hi everyone,

I used "plot" for drawing 2 two curve in one plot. I got it but one from these (red line) is not beautiful (the curve is not smooth) and I didn't understand why in area legend's didn't show green line. Anyone help me please. Below show the code I did. Thank you for advance.

clear all;
clc;
hold on
kr=[0 10 20 30 40 50 60 70 80 90];
M1=[0    0.2757    0.4979    0.4989    0.4481    0.3644    0.2910    0.2228    0.1380    0.0346];
M2=[0    0.0241    0.0916    0.1786    0.2613    0.3322    0.3895    0.4343    0.4658    0.4809];
 plot(kr,M1,'x',0:90, interp1(kr,M1,[0:90],'spline'),'r','linewidth',1.5);
 plot(kr,M2,'x',0:90, interp1(kr,M2,[0:90],'spline'),'g','linewidth',1.5); 
  grid on 
  xlabel('heel angel')
  ylabel('arm')
  legend('ld','ls','Location','northwest')
  title('Diagram stability')

Answer 1

If you want the red and green lines to show, you need to plot them separately, and create handles for them to pass to the legend call:

hold on
kr=[0 10 20 30 40 50 60 70 80 90];
M1=[0    0.2757    0.4979    0.4989    0.4481    0.3644    0.2910    0.2228    0.1380    0.0346];
M2=[0    0.0241    0.0916    0.1786    0.2613    0.3322    0.3895    0.4343    0.4658    0.4809];
plot(kr,M1,'x')
hp1 = plot(0:90, interp1(kr,M1,[0:90],'spline'),'r','linewidth',1.5);
plot(kr,M2,'x')
hp2 = plot(0:90, interp1(kr,M2,[0:90],'spline'),'g','linewidth',1.5); 
grid on
xlabel('heel angel')
ylabel('arm')
legend([hp1 hp2], 'ld','ls','Location','northwest')
title('Diagram stability')

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