# I got the problem with polyshape, please help me

조회 수: 12(최근 30일)
Thai Anh 2022년 12월 4일
편집: Stephan 2022년 12월 5일
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);
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Thai Anh 2022년 12월 4일
oh I'm sorry.
The demand is sketch the domain D be the region bounded by

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### 채택된 답변

Stephan 2022년 12월 4일
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...
##### 댓글 수: 12표시숨기기 이전 댓글 수: 11
Stephan 2022년 12월 5일
편집: Stephan 2022년 12월 5일
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);
M = polyshape([x_linear, x_quad], [y_linear, y_quad],'simplify', false);
plot(x,y1,x,y2)
hold on
plot(M)

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