Defines the equation used by a formula. Read/write String.

Applies To

F (subelement of Formulas)

Tag Syntax

<v: element eqn="expression">

Script Syntax

element.eqn="expression"

expression=element.eqn

Remarks

Equations are defined by the evaluation of a text expression that has the general form of an operation followed by up to three arguments. Each argument may be of the following types:

• adjustment (for example, #2)
• another formula (for example, @2)
• fixed numbers (for example, 2)
• predefined values

The table below defines the formulas that can be used with the optional arguments given the names v , p1, and p2. The formula pattern is:

   <f eqn="operation [v] [p1] [p2]"/>

Operation	Params	Exact	Result	Description
val	1	yes	v	Defines a guide value from some other value.
sum	3	yes	v + p1 - p2	Used for addition and subtraction.
product	3	rounds	v * p1 / p2	Used for multiplication and division.
mid	2	(c)	(v + p1) / 2	Average.
abs	1	yes	abs(v)	Absolute value.
min	2	yes	min(v,p1)	The lesser value of v and p1.
max	2	yes	max(v,p1)	The greater value of v and p1.
if	3	yes	v > 0 ? p1 : p2	Conditional testing.
mod	3	no	sqrt(v^2 + p1^2 + p2^2)	Modulus value.
atan2	2	no	atan2(p1,v)	Polar value in degrees * 2^16 (fd units).
sin	2	no	v * sin(p1)	Sin, argument in degrees * 2^16 (fd units).
cos	2	no	v * cos(p1)	Cos, argument in degrees * 2^16 (fd units).
cosatan2	3	no	v * cos(atan2(p2,p1))	Preserves full accuracy in intermediate calculation.
sinatan2	3	no	v * sin(atan2(p2,p1))	Preserves full accuracy in intermediate calculation.
sqrt	1	no	sqrt(v)	Result is positive and rounds down.
sumangle	3	yes	v + p1 * 2^16 + p2*2^16	v scaled by 2^16; p1 and p2 are degrees.
ellipse	3	no	p2 * sqrt(1-(v/p1)^2)	Ellipse.
tan	2	no	v * tan(p1)	Tangent, argument in degrees * 2^16 (fd units).

Note that the equation only consists of operations and numbers; mathematical symbols are omitted. For example, the equation

   eqn="sum 5 9 3"

would yield the equivalent of

   5 + 9 - 3

for the returned value of 11. If operands are missing, the value is not used. For example,

   eqn="sum 5 9"

would yield the equivalent of

   5 + 9

and would ignore the missing operand.

VML Standard Attribute

Example

The following formula would yield a result of 6 (the sum of both numbers divided by 2), which, if this were the first formula, could be retrieved by the symbol @0.

   <v:f eqn="mid 5 7"/>