Adding different colors to the same plotting line

Hi MATLAB community, I am trying to add different colors to the same plot line. I want a color for 0<x<100, another color for 100<x<150, and another color for 150<x<200. Here is my code:

clear
clc

dx = 200/1000;
x = 0:dx:200;
for k = 1:length(x)
    if x(k) <= 100
      y(k) = sqrt(x(k));
    end
    if x(k) >100 && x(k)<=150
       y(k) = (2*x(k))-190;
    end
    if x(k) > 150
        y(k)=110;
    end
end
plot(x,y,'color',rand(1,3),'DisplayName', '\surd(x)')
legend('-DynamicLegend')
hold all
plot(x,y,'color',rand(1,3),'DisplayName', '2x')
plot(x,y,'color',rand(1,3),'DisplayName', 'Constant')
xlabel('x'), ylabel('y')

Answer 1

[Adam Danz]

The variables idx1, idx2, idx3 replace your for-loop and mark the indices of x and y that are categorized by your logical expressions. You can use them to calculate Y and to plot the 3 portions of the line with different colors.

clear
clc
dx = 200/1000;
x = 0:dx:200;

idx1 = x <= 100; 
idx2 = x > 100 & x <= 150; 
idx3 = x > 150; 

y = nan(size(x)); 
y(idx1) = sqrt(x(idx1));
y(idx2) = (2.*x(idx2))-190;
y(idx3) = 110;


plot(x(idx1),y(idx1),'color',rand(1,3),'DisplayName', '\surd(x)')
legend('-DynamicLegend','Location','NorthWest')
hold all
plot(x(idx2),y(idx2),'color',rand(1,3),'DisplayName', '2x')
plot(x(idx3),y(idx3),'color',rand(1,3),'DisplayName', 'Constant')
xlabel('x'), ylabel('y')

[Hermes Chirino]

great, it worked, thanks Adam.

[Adam Danz]

Great!