Defining Dimensional Constraints Parameters

You can control Dimensional Constraint geometry with mathematical equations and expressions.

Parametric equations include:

  • The names of the Dimensional Constraints

  • Expressions, in which you can use:

    • Values

    • User-defined variables, and variables that represent existing Dimensional Constraints

    • Mathematical operators, functions, and constants

Expressions for Dimensional Constraints

When you create a Dimensional Constraint, an equation defines the dimension of an entity or between points on entities in the form name*=*value, for example d1*=*12.34.

You can replace the value by an expression: name*=*expression.

  • Within the expression, you can use values, variables, mathematical operators, and mathematical functions and constants.

  • The result of an expression is a value.

A variable can be one of the following:

  • User-defined, for example length1*=*12.5

  • An existing Dimensional Constraint name, for example d2*=*rad1

Use the Parameters Manager to define and edit expressions and variables.

You can also edit expressions in-place.

Dimensional Constraints Equation Examples

Example

Description

d1=rad1

Sets the variable d1 to the value of the variable rad1.

d2=rad2*2

Multiplies the variable rad2 by 2 and sets the variable d2 as the result.

length1=cos(ang1)

Sets the user-defined variable length1 to the value of the cosine of angle ang1.

dist1=(length1 + d1) / 2

Sets the user-defined variable dist1 to the sum of the user-defined variable length1 and the variable d1 divided by 2.

Constraint Names

Dimensional Constraints (both Dynamic and Annotation constraints) are identified by name, as well as user-defined variables used in expressions and formulas.

The Parameters Manager lists all Dimensional Constraints variables with their names, expressions, and values.

The naming conventions are:

Meaning

Default Name

Constraints

Distance

d1, d2, …, d*n*

Aligned, Horizontal, Vertical

Diameter

dia1, dia2, …, dia*n*

Diameter

Radius

rad1, rad2, …, rad*n*

Radial

Angle

ang1, ang2, …, ang*n*

Angular

User-defined

user1, user2, …, user*n*

Used in expressions

To rename constraint variable names:

  1. Specify a Dimensional Constraint.

  2. In the Properties palette, under Constraint, edit the Name.

  • or -

  1. Specify a Dimensional Constraint.

  2. In the Parameter Manager palette, under Dimensional Constraints, edit the Name.

  • or -

  1. Double-click a Dimensional Constraint.

  2. Edit the variable name in place.

Note: Constraint variable names must be unique.

Parametric Equations

Use operators and functions to define formulas and equations.

The evaluation of expressions follows standard mathematical rules.

Operators

You can use the following operators in expressions and formulas:

Operator

Description

+

Addition

-

Subtraction (or unary negation)

*

Multiplication

/

Division

^

Exponentiation

%

Floating point modulo

.

Decimal separator

(expr)

Parentheses to define expressions

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Functions

You can use the following functions in expressions and formulas:

Function

Syntax

Cosine

cos (expr)

Sine

sin (expr)

Tangent

tan (expr)

Arc cosine

acos (expr)

Arc sine

asin (expr)

Arc tangent

atan (expr)

Hyperbolic cosine

cosh (expr)

Hyperbolic sine

sinh (expr)

Hyperbolic tangent

tanh (expr)

Arc hyperbolic cosine

acosh (expr)

Arc hyperbolic sine

asinh (expr)

Arc hyperbolic tangent

atanh (expr)

Square root

sqrt (expr)

Signum function (-1,0,1)

sign (expr)

Absolute value

abs (expr)

Truncate decimal

trunc (expr)

Round to nearest integer

round (expr)

Round down

floor (expr)

Round up

ceil (expr)

Largest element in array

max (expr1;*expr2*) *

Smallest element in array

min (expr1;*expr2*) *

Degrees to radians

d2r (expr)

Radians to degrees

r2d (expr)

Logarithm, base e

ln (expr)

Logarithm, base 10

log (expr)

Exponent, base e

exp (expr)

Exponent, base 10

exp10 (expr)

Power function

pow (expr1;*expr2*) *

Random decimal, 0-1

random

Constant pi

pi

Constant e

e

*) Uses the list separator (semicolon or comma) as defined in the OS format settings.

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Expression Evaluation

According to standard mathematical rules expressions are evaluated using the following precedence:

  1. Expressions within parentheses (innermost parentheses first)

  2. Standard operations order:

    1. Exponents

    2. Multiplication and division

    3. Addition and subtraction

  3. Operators of equal precedence from left to right.

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Related Topics

Managing Dimensional Constraint Parameters

Working with Constraints

Parent Topic

Applying Dimensional Constraints