I got the problem with polyshape, please help me

12 views (last 30 days)
Demand: sketch the domain D be the region bounded by
My code:
x1 = 0:1:30;
y1 = 2-x1;
y2 = sqrt(x1).*(12-x1)./2;
xcut = fzero(@(x)sqrt(x).*(12-x)./2 - 2+x, 0.5);
x = [x1(x1<=xcut), x1(end)];
y = [sqrt(x1).*(12-x1)./2 (x1<=xcut), 2-x1(end)];
M = polyshape(x,y);
plot(x1,y1,x1,y2,x,y)
hold on
plot(M)
hold off
xlim([0,30])
ylim([0,30])
Error:
Error using polyshape/getXY
x- and y-coordinates must be vectors of the same size with at least 3 elements.
Error in polyshape/checkInput (line 842)
[X, Y, xy2input, next_arg] = polyshape.getXY(varargin{:});
Error in polyshape (line 169)
[X, Y, tc, simpl, collinear] = polyshape.checkInput(param, varargin{:});
Error in bai4 (line 7)
M = polyshape(x,y);
  4 Comments
Thai Anh
Thai Anh on 4 Dec 2022
oh I'm sorry.
The demand is sketch the domain D be the region bounded by

Sign in to comment.

Accepted Answer

Stephan
Stephan on 4 Dec 2022
You have to take both points into account to find a closed region:
xcut1 = fzero(@(x)sqrt(x).*(12-x)./2 - 2+x, 0.5);
xcut2 = fzero(@(x)sqrt(x).*(12-x)./2 - 2+x, 20);
I had the code ready here - but homework is homework... I leave the rest to you. It should be easy now...
  12 Comments
Thai Anh
Thai Anh on 5 Dec 2022
x1 = 0:1:30;
y1 = 2-x1;
y2 = sqrt(x1).*(12-x1)./2;
xcut1 = fzero(@(x)sqrt(x).*(12-x)./2 - 2+x, 0.5);
xcut2 = fzero(@(x)sqrt(x).*(12-x)./2 - 2+x, 20);
a=[x1(xcut1<=x1),x1(x1<=xcut2)];
b=[2-x1 (x1>=xcut1), 2-x1 (x1<=xcut2)] ;
M = polyshape(a,b);
plot(M)
hold on;
grid on;
xlim([0,30])
ylim([0,30])
..... I tried but I cannot mark the curve region
Stephan
Stephan on 5 Dec 2022
Edited: Stephan on 5 Dec 2022
Sorry, last try - i can not make it more clear without doing your homework:
x = -10:1:10;
y1 = -x.^2 + 100;
y2 = 0.*x + 50;
xcut1 = fzero(@(x)-x.^2 + 100 - 50,-7);
xcut2 = fzero(@(x)-x.^2 + 100 - 50,7);
x_linear = [xcut1 xcut2];
y_linear = [50 50];
x_quad = linspace(xcut1, xcut2, 25);
y_quad = -x_quad.^2 + 100;
M = polyshape([x_linear, x_quad], [y_linear, y_quad],'simplify', false);
plot(x,y1,x,y2)
hold on
plot(M)

Sign in to comment.

More Answers (0)

Categories

Find more on Numerical Integration and Differential Equations in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!