yieldstress = 333.8624; a1 = -0.1039; limitxy = 500; vmc = @(x, y) sqrt(x.^2 - x.y + y.^2) - yieldstress.(1+a1*(-sqrt(3)/3)); xx = linspace(-limitxy, limitxy, 1000); yy = linspace(-limitxy, limitxy, 1000); [X, Y] = ndgrid(xx, yy); [C, h] = contour(X, Y, vmc(X, Y), [1 1]); h.LineWidth = 1; h.EdgeColor = "b"; h.FaceColor = "r";，给绘制的曲线添加符号标记

可以使用 `plot` 函数在曲线上添加符号标记，代码如下：

yieldstress = 333.8624;
a1 = -0.1039;
limitxy = 500;

vmc = @(x, y) sqrt(x.^2 - x.*y + y.^2) - yieldstress.*(1+a1*(-sqrt(3)/3));

xx = linspace(-limitxy, limitxy, 1000);
yy = linspace(-limitxy, limitxy, 1000);
[X, Y] = ndgrid(xx, yy);

[C, h] = contour(X, Y, vmc(X, Y), [1 1]);
h.LineWidth = 1;
h.EdgeColor = "b";
h.FaceColor = "r";

% 添加符号标记
hold on;
plot(0, 0, "o", "MarkerSize", 8, "MarkerFaceColor", "g", "MarkerEdgeColor", "k");
hold off;