entering an expression in the Command prompt calculator, you can
quickly solve a mathematical problem or locate points in your drawing.
The CAL command runs
the 3D calculator utility to evaluate vector expressions (combining
points, vectors, and numbers) and real and integer expressions.
The calculator performs standard mathematical functions. It also
contains a set of specialized functions for calculations involving
points, vectors, and AutoCAD LT geometry. With the CAL command,
- Calculate a vector from two points, the
length of a vector, a normal vector (perpendicular to the XY plane),
or a point on a line
- Calculate a distance, radius, or angle
- Specify a point with the pointing device
- Specify the last-specified point or intersection
- Use object snaps as variables in an expression
- Convert points between a UCS and the
- Filter the X, Y,
and Z components of a vector
- Rotate a point around an axis
CAL evaluates expressions according to standard
mathematical rules of precedence.
Mathematical operators in order of precedence
Indicates numeric exponent
Multiplies and divides numbers
Adds and subtracts numbers
You can use CAL whenever you need to calculate
a point or a number within a command.
For example, you enter (mid+cen)/2 to specify
a point halfway between the midpoint of a line and the center of
The following example uses CAL as a construction
tool. It locates a center point for a new circle, and then calculates
one fifth of the radius of an existing circle.
Here is the command prompr sequence:
Specify center point
for circle or [3P/2P/Ttr (tan tan radius)]: 'cal
>> Expression: (mid+cen)/2
>> Select entity
for MID snap: Select the notch line (1)
>> Select entity
for CEN snap: Select the large circle (2)
>> Expression: 1/5*rad
>> Select circle,
arc or polyline segment for RAD function: Select the large circle
Expressions in a Dialog Box
can also enter and evaluate mathematical expressions in a dialog
box using the following format: =expression<Alt+Enter>.
NoteTo evaluate expressions
in a dialog box, make sure the system variable, CALCINPUT, is set
To start the Command prompt