@@ -78,10 +80,10 @@ i.e. each coordinate is defined with relation to "current pen position".
Each integer or floating value may be represented as
* Integer or floating literal (usual python syntax, such as 5 or 7.5)
* Variable name, such as `a` or `b` or `variable_name`
* Negation sign and a variable name, such as `-a` or `-size`.
* Expression enclosed in curly brackets, such as `{a+1}` or `{sin(phi)}`
* Integer or floating literal (usual python syntax, such as 5 or 7.5)
* Variable name, such as `a` or `b` or `variable_name`
* Negation sign and a variable name, such as `-a` or `-size`.
* Expression enclosed in curly brackets, such as `{a+1}` or `{sin(phi)}`
ArcTo only take enough parameters to complete one Arc, unlike real SVG command
which take a whole sequence of chained ArcTo commands. The decision
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@@ -107,12 +109,15 @@ directory in Sverchok distribution.
Expression syntax
-----------------
Syntax being used for formulas is standard Python's syntax for expressions.
Syntax being used in profile definitions is standard Python's syntax for expressions.
For exact syntax definition, please refer to https://docs.python.org/3/reference/expressions.html.
In short, you can use usual mathematical operations (`+`, `-`, `*`, `/`, `**` for power), numbers, variables, parenthesis, and function call, such as `sin(x)`.
In short, you can use usual mathematical operations (`+`, `-`, `*`, `/`, `**`
for power), numbers, variables, parenthesis, and function call, such as
`sin(x)`.
One difference with Python's syntax is that you can call only restricted number of Python's functions. Allowed are:
One difference with Python's syntax is that you can call only restricted number
of Python's functions. Allowed are:
- Functions from math module:
- acos, acosh, asin, asinh, atan, atan2,
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@@ -126,15 +131,19 @@ One difference with Python's syntax is that you can call only restricted number
- From mathutlis module: Vector, Matrix;
- Python type conversions: tuple, list.
This restriction is for security reasons. However, Python's ecosystem does not guarantee that noone can call some unsafe operations by using some sort of language-level hacks. So, please be warned that usage of this node with JSON definition obtained from unknown or untrusted source can potentially harm your system or data.
This restriction is for security reasons. However, Python's ecosystem does not
guarantee that noone can call some unsafe operations by using some sort of
language-level hacks. So, please be warned that usage of this node with profile
definition obtained from unknown or untrusted source can potentially harm your
system or data.
Examples of valid expressions are:
* 1.0
* x
* x+1
* 0.75*X + 0.25*Y
* R * sin(phi)
* {x+1}
* {0.75*X + 0.25*Y}
* {R * sin(phi)}
Inputs
------
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@@ -284,9 +293,9 @@ Gotchas
The update mechanism doesn't process inputs or anything until the following conditions are satisfied:
* All inputs have to be connected, except ones that have default values
declared by "default" statements.
* The file field on the Node points to an existing Text File.
* All inputs have to be connected, except ones that have default values
declared by "default" statements.
* The file field on the Node points to an existing Text File.
