**Geometric
Calculator**

Comments by: Odin Cary

This is one of the most overlooked commands in AutoCAD and unfortunately one of the most valuable tools.

Embedded within AutoCAD lies a calculator that cannot only be used for basic arithmetic functions, but also trigonometric functions, unit conversions and advanced geometric functions.

One function alone has made this tool invaluable to me and I will start with that simple routine.

**1**Example

Draw a square or rectangle.

Now put a circle in the exact center of that polygon.

Here's how you can do it with the Geometric Calculator:

Command:circle

CIRCLE 3P/2P/TTR/<Center point>:'cal

Initializing...>> Expression:mee

>> Select one endpoint for MEE:(pick one corner)

>> Select another endpoint for MEE:(pick another corner diagonally opposite from the first)

Diameter/<Radius>:

What you have just done:

The Geometric Calculator was
invoked transparently after the circle command ( **'cal **)
and then utilized to perform a point calculation: the midpoint
between two endpoints (hence the expression **mee**).
You were queried for two points in exactly the same fashion you
are queried for two object snap points. Notice that the Geometric
Calculator quires for points with a pick box slightly larger than
normal.

You can use this technique to find the midpoint between any two points anywhere in an AutoCAD drawing. It is fantastic when mirroring objects.

**2**Example

Have I gotten your attention yet?

Well, here's another great time saver.

Draw a horizontal line.

Draw another vertical line off of one of the endpoints of the previous horizontal line.

Now offset the last line 1/3 of the way down the horizontal line.

Here's how you can do it with the Geometric Calculator:

Command:OFFSET

Offset distance or Through <Through>:'cal

>> Expression:dist(end,end)/3

>> Select entity for END snap:( pick one endpoint[1])

>> Select entity for END snap:( pick the other endpoint[2])

Select object to offset:( pick the vertical line[3])

Side to offset?( pick in the direction of offset[4])

Select object to offset:

What you have just done:

The Geometric Calculator was
invoked transparently after the Offset command and utilized to
calculate the **dist**ance of the horizontal line,
based upon its **end**points, and divided that
distance by **3**. The Offset command then received
the calculated distance and allowed you to offset an object by
that amount.

You can divide the distance by any
number you want and you can also specify a distance by any object
snap; e.g., **dist(mid,quad)/10**.

**3**General summary of the Geometric Calculator
excerpted from class notes.

**The Geometric Calculator:**

A basic calculator and unit converter

Command: cal

>> Expression: cos(45)

0.707107

+, -, *, /, ^, (), pi

CVUNIT(value, unit_type, to what unit_type)

Command: cal

>> Expression: cvunit(2,m,ft)

6.56168

Acquiring the Midpoint of any two points in space.

Command:

l

LINE From point:'cal

>> Expression:(end+end)/2

>> Select entity for END snap:

>> Select entity for END snap:

To point:

Acquiring the Centroid of any **REGULAR**
Polygon

Command:

MOVE

Select objects: 1 found

Select objects:

Base point or displacement:'cal

>> Expression:(end+end+end)/3

>> Select entity for END snap:

>> Select entity for END snap:

>> Select entity for END snap:

Second point of displacement:

**Pre-designed Functions for the
Geometric Calculator:**

- MEE => Midpoint of two Endpoints => (end+end)/2
- ILLE => Intersection of two lines based upon selected endpoints
- ILL => same as ILLE but requires point specifications; e.g. ILL(int,end,mid,qua)
- DEE => Distance between two Endpoints => Dist(end,end)
- NEE => Normal vector off of two Endpoints => Nor(end,end)
- VEE => Vector off of two Endpoints => Vec(end,end)
- VEE1 => Unit Vector off of two Endpoints => Vec1(end,end)

These Functions can be used as per the following example:

Command:

c

CIRCLE 3P/2P/TTR/<Center point>:'cal

>> Expression:mee

>> Select one endpoint for MEE:

>> Select another endpoint for MEE:

Diameter/<Radius>:

**Other Useful Functions for the
Geometric Calculator**

ANG(ApexPt

_{1}, Pt_{2}, Pt_{3}) => Returns the Angle derived by 3 points in space; e.g., ANG(int, end, end). Pt_{2 }to Pt_{3 }direction will determine value of angle relative to AutoCAD’s counter clockwise "Angle Direction" Default Setting.

PLD(Pt

_{1}, Pt_{2}, Distance_Value) => Returns a point along a line based upon the Distance_Value relative to the First Point (Pt_{1}) and the angle determined by the Second Point (Pt_{2 }); e.g., PLD(end,end,3) will return a point on a line 3 units from the First Point selected.