# 微积分网课代修|偏微分方程代写Partial Differential Equation代考|SCEE09004 Specify Geometry Using a CSG Model

• 单变量微积分
• 多变量微积分
• 傅里叶级数
• 黎曼积分
• ODE
• 微分学

## 微积分网课代修|偏微分方程代写Partial Differential Equation代考|Specify Geometry Using a CSG Model

For basic information on 2-D geometry construction, see “Create 2-D Geometry” on page 2-17
You can specify complex geometries by overlapping solid objects. This approach to representing geometries is called Constructive Solid Geometry (CSG).
Use these four solid objects to specify a geometry for your problem:

• Circle – Represents the set of points inside and on a circle.
• Polygon – Represents the set of points inside and on a polygon given by a set of line segments.
• Rectangle – Represents the set of points inside and on a rectangle.
• Ellipse – Represents the set of points inside and on an ellipse. The ellipse can be rotated.

When you draw a solid object in the PDE app, each solid object is automatically given a unique name. Default names are C1, C2, C3, etc., for circles; P1, P2, P3, etc. for polygons; R1, R2, R3, etc., for rectangles; E1, E2, E3, etc., for ellipses. Squares, although a special case of rectangles, are named SQ1, SQ2, SQ3, etc. The name is displayed on the solid object itself. You can use any unique name, as long as it contains no blanks. In draw mode, you can alter the names and the geometries of the objects by double-clicking them, which opens a dialog box. The following figure shows an object dialog box for a circle.

## 微积分网课代修|偏微分方程代写Partial Differential Equation代考|Select Graphical Objects Representing Your Geometry

Throughout the PDE app, similar principles apply for selecting objects such as solid objects, subdomains, and boundaries.

• To select a single object, click it using the left mouse button.
• To select several objects and to deselect objects, Shift+click (or click using the middle mouse button) on the desired objects.
• Clicking in the intersection of several objects selects all the intersecting objects.
• To open an associated dialog box, double-click an object. If the object is not selected, it is selected before opening the dialog box.
• In draw mode and PDE mode, clicking outside of objects deselects all objects.
• To select all objects, use the Select All option from the Edit menu.
• When defining boundary conditions and the PDE via the menu items from the Boundary and PDE menus, and no boundaries or subdomains are selected, the entered values applies to all boundaries and subdomains by default.

## 微积分网课代修|偏微分方程代写Partial Differential Equation代考|Specify Geometry Using a CSG Model

• 圆 – 表示圆内和圆上的点集。
• 多边形 – 表示由一组线段给出的多边形内部和上面的一组点。
• 矩形 – 表示矩形内部和矩形上的点集。
• 椭圆 – 表示椭圆内部和椭圆上的点集。椭圆可以旋转。

## 微积分网课代修|偏微分方程代写Partial Differential Equation代考|Select Graphical Objects Representing Your Geometry

• 要选择单个对象，请使用鼠标左键单击它。
• 要选择多个对象并取消选择对象，请按住 Shift 并单击（或使用鼠标中键单击）所需的对象。
• 单击几个对象的交集会选择所有相交的对象。
• 要打开相关对话框，请双击对象。如果对象未被选中，则在打开对话框之前将其选中。
• 在绘图模式和 PDE 模式下，单击对象外部会取消选择所有对象。
• 要选择所有对象，请使用“编辑”菜单中的“全选”选项。
• 通过 Boundary 和 PDE 菜单中的菜单项定义边界条件和 PDE 时，如果没有选择边界或子域，则输入的值默认适用于所有边界和子域。