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

Question

Maxtron Moon 2020-6-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/556987-how-to-show-only-parts-of-a-function-in-a-plot-in-order-to-combine-functions

评论： Maxtron Moon 2020-6-30

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')

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Maxtron Moon 2020-6-30

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 2020-6-30

Do you have this program?

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Answer 1

Kevin Joshi 2020-6-30

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/556987-how-to-show-only-parts-of-a-function-in-a-plot-in-order-to-combine-functions#answer_458971

在 MATLAB Online 中打开

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')