How to show only parts of a function in a plot, in order to combine functions?

Hi everyone,

I need some help with this. I got three functions, but I want to plot only part of them and stich them together. This is the code and the figure. So I want the blue line to go up to the intersection with the red line (1,0101,1,0203) and I want the other two plots to not show in this region. Then, from that intersection point, I want the red line to go up to the intersection (5,4545, 3,5692) while omiting the other functions in this interval and thirdly, after this interaction, I want the graph to show only the black line. Is that possible?

x=linspace(0,20)
y=x.^4.*exp(-x);
plot(x,y,'k')
grid on
hold on
y=x.^(3/4);
plot(x,y,'r')
axis([ 0 20 10^(-2) 10^2])
hold on 
y=x.^2;
plot(x,y,'b')
set(gca, 'YScale', 'log')
set(gca, 'XScale', 'log')

[darova]

Can you make a simple sketch of the result picture?

[Maxtron Moon]

It would look something like this (you know the units and curves are not the same) but basically I want to combine it in this way; the first interval would consist of the blue line, the second of the red and the last of the black line all stiched together to look like a single function)

[darova]

Do you have this program?

Answer 1

[Kevin Joshi]

clc;
clear all;

%%
x=linspace(0,20);
y1=x.^4.*exp(-x);
y2=x.^(3/4);
y3=x.^2;

%%
x=linspace(0,20);
[x12,y12] = intersections(x,y1,x,y2,1)
[x23,y23] = intersections(x,y2,x,y3,1)

x3_3 = 0:0.0001:x23(2);
y3_3 = x3_3.^2;
p1 = plot(x3_3,y3_3,'b','LineWidth',1);
hold on
x2_2 = x23(2):0.0001:x12(3);
y2_2 = x2_2.^(3/4);
p2 = plot(x2_2,y2_2,'r','LineWidth',1);

x3_3 = x12(3):0.0001:20;
y3_3 = x3_3.^4.*exp(-x3_3);
p3 = plot(x3_3,y3_3,'k','LineWidth',1);

datatip(p3,x2_2(end),y2_2(end))

axis([10^-2 20 10^(-2) 10^2])
grid on;
set(gca, 'YScale', 'log')
set(gca, 'XScale', 'log')

I have used

https://in.mathworks.com/matlabcentral/fileexchange/11837-fast-and-robust-curve-intersections

to find line intersections.

[Maxtron Moon]

Thank you very much! This is exactly what I been looking for! God bless...