Fill Area in matlab plot

Question

Szczepan Letkiewicz 2021-12-10

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1608055-fill-area-in-matlab-plot

评论： Szczepan Letkiewicz 2021-12-10

Hello. Im trying to fill an area between two curves in Matlab, from a certain x-value to another. The problem im encountering is that my fill area is being compressed, I think im going about this wrong. My idea was to also make two fill areas so that I could change their colors but I encountered this problem before hand. I have added my code below and a picture of what im trying to recreate for referance.

clear; clc; close all;

x = 0:0.01:5;

Y1= -0.2*x+4;

Y2= -0.2*x+2;

Y3= (nthroot((x-2.5),3))+2.5;

idx = find(Y2 - Y3 < eps, 1);

px = x(idx);

py = Y2(idx);

x_1 = linspace(0,px,501);

plot(x,Y1,'b',x,Y2,'r',x,Y3,'k');

hold on

fill([x_1 fliplr(x_1)],[Y3 fliplr(Y2)],'c')

My end goal is to replace the function "Y3" with a set of data that and have matlab plot the two areas. The lines in my code lablled as "Y1" and "Y2" are just example for now my plan is to calculate them once I get my data. If there is a way to make Matlab extrapolate them from the data that I will get then that would be amazing.

Thank you for the help in advance.

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Answer 1

KSSV 2021-12-10

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1608055-fill-area-in-matlab-plot#answer_852235

在 MATLAB Online 中打开

Download the function InterX from the link: https://in.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections

x = 0:0.01:5;
Y1= -0.2*x+4;
Y2= -0.2*x+2;
Y3= (nthroot((x-2.5),3))+2.5;
idx = find(Y2 - Y3 < eps, 1);
px = x(idx);
py = Y2(idx);
x_1 = linspace(0,px,501);
x1 = 2.5*ones(1,10); 
y1 = linspace(1,4,10) ; 
plot(x,Y1,'b',x,Y2,'r',x,Y3,'k',x1,y1,'g');
hold on
A = InterX([x;Y2],[x;Y3]) ;
B = InterX([x;Y2],[x1;y1]) ; 
C = InterX([x1;y1],[x;Y3]) ;
D = InterX([x1;y1],[x;Y1]);
E = InterX([x;Y1],[x;Y3]) ;
xi = linspace(A(1),E(1)) ;
yi = interp1(x,Y3,xi) ; 
Rx = [A(1) B(1) D(1) E(1) fliplr(xi)] ;
Ry = [A(2) B(2) D(2) E(2) fliplr(yi)] ;
patch(Rx,Ry,'y')