How can i fill the common areas of two curves?

y1 = @(x) 3*x.^2 + 2*x +1;
y2 = @(x) -5*x.^2 + x + 20;
x = -5:0.1:5;
pgon1 = polyshape(x,y1(x));
pgon2 = polyshape(x,y2(x));
figure
plot(x,y1(x),x,y2(x))
hold on
plot(intersect(pgon1,pgon2),'EdgeColor','none')

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byungkeuk cho 2019-3-20

One more question plz.

How can i change the colar of the shade?

Akira Agata 2020-6-15

在 MATLAB Online 中打开

You can change the color by setting FaceColor option, like:

...
plot(intersect([pgon1,pgon2,pgon3]),'EdgeColor','none','FaceColor','m')

More details can be foun in the documentation page.

https://jp.mathworks.com/help/matlab/ref/polyshape.plot.html

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Answer 2

byungkeuk cho 2019-3-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/450852-how-can-i-fill-the-common-areas-of-two-curves#answer_366273

I am trying to shade the triangle between three lines.

but it is not working.

y1 = @(x) x ;

y2 = @(x) sqrt(3)/2*x ;

y3 = @(x) -x + 1 ;

x = 0:0.1:2;

pgon1 = polyshape(x,y1(x));

pgon2 = polyshape(x,y2(x));

pgon3 = polyshape(x,y3(x));

figure

plot(x,y1(x),x,y2(x),x,y3(x))

hold on

plot(intersect([pgon1,pgon2,pgon3]),'EdgeColor','none ')

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byungkeuk cho 2019-3-20

I really appreciate it.

Rahman 2020-6-14

在 MATLAB Online 中打开

Mr. Akira Agata, I've a code that generates 2 curves and have an intersection point. How can I show the area on the right of the intersection as 'hatched grey'?

M = [0.54, 0.7, 0.74, 0.78];
X1 = [0.007856, 0.008394, 0.008607, 0.012584];      %X1 values
X2 =  [0.007901, 0.008461, 0.008739, 0.011302];      %X2 values
xq = linspace(M(1), M(end), 1000);   %adding intervals to make line smoother
X3 = interpn(M,X1,xq,'pchip');  %other type: pchip, makima, spline etc.
X4 = interpn(M,X2,xq,'pchip');  %other type: pchip, makima, spline etc.
set(0,'defaulttextinterpreter','latex')
figure(1)
hold all; 
plot(xq, X3,'r-','LineWidth',2);
plot(xq, X4,'b--','LineWidth',2);
X=[xq,fliplr(xq)];           %create continuous x value array for plotting
Y=[X3,fliplr(X4)];           %create y values for out and then back
fill(X,Y,'g');    %plot filled area
xlabel('X','FontSize',12); % Label the x axis
ylabel('Y','FontSize',12); % Label the y axis

The code above generates following figure: (the whole area between 2 curves is shaded as green)

However, I'd like to have the right area after intersection (roughly from X = 0.75 to 0.78) shaded only. Also, in the plot above, I need to change the shaded area on the right after intersection (roughly from X = 0.75 to 0.78) as 'hatched grey'.

Any help will be appreciated.

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