| r = 0 : 0.2:sqrt(2); |
| t = 0 : 0.2 : 2 pi + 0.2; | [T, R] = mesh grid(t, r); | X = cos(T). R; | Y = sin(T). R; | Z = X.^2 + 2 Y.^2 | axis([−3, 3, −3, 3, −15]); | hold on; | quiver3(0, 0, 0, −1.5, 0, 0, 2.2, “k,” “filled” “LineWidth,”1.6) | quiver3(0, 0, 0, 0, −1.5, 0, 2.2, “k,” “filled” “LineWidth”, 1.6) | quiver3(0, 0, 0, 0, 0, 0, 2.5, 3, “k,” “filled” “LineWidth,” 1.6) | text(0, −0.6, 8, “Z”); | text(0, −4, 0, “Y”); | text(−4, 0, 0.2, “X”); | axis off; | hold on; | set(gef, “color,”[1 1 1]); | surf(X, Y, Z, “FaceColor,” “g”); | z = 6-2 X.^2- Y.^2 | surf(X, Y, Z, “EdgeColor,””None”); | hold on; | X = squrt(2) cos(t) | Y = squrt(2) sin(t) | Z = X.^2 + 2 Y.^2; | plot3(X, Y, Z, “k”,”LineWidth,” 3); | hold on; | view(0, 90) |
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