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"/>