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78 lines
2.2 KiB
Markdown
78 lines
2.2 KiB
Markdown
<!-- Note: This file is automatically generated from source code comments. Changes made in this file will be overridden. -->
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# Function simplify
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Simplify an expression tree.
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A list of rules are applied to an expression, repeating over the list until
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no further changes are made.
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It's possible to pass a custom set of rules to the function as second
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argument. A rule can be specified as an object, string, or function:
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var rules = [
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{ l: 'n1*n3 + n2*n3', r: '(n1+n2)*n3' },
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'n1*n3 + n2*n3 -> (n1+n2)*n3',
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function (node) {
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// ... return a new node or return the node unchanged
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return node
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}
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]
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String and object rules consist of a left and right pattern. The left is
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used to match against the expression and the right determines what matches
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are replaced with. The main difference between a pattern and a normal
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expression is that variables starting with the following characters are
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interpreted as wildcards:
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- 'n' - matches any Node
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- 'c' - matches any ConstantNode
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- 'v' - matches any Node that is not a ConstantNode
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The default list of rules is exposed on the function as `simplify.rules`
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and can be used as a basis to built a set of custom rules.
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For more details on the theory, see:
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- [Strategies for simplifying math expressions (Stackoverflow)](http://stackoverflow.com/questions/7540227/strategies-for-simplifying-math-expressions)
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- [Symbolic computation - Simplification (Wikipedia)](https://en.wikipedia.org/wiki/Symbolic_computation#Simplification)
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## Syntax
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```js
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simplify(expr)
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simplify(expr, rules)
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simplify(expr, rules, scope)
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simplify(expr, scope)
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```
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### Parameters
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Parameter | Type | Description
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--------- | ---- | -----------
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`expr` | Node | string | The expression to be simplified
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`rules` | Array<{l:string, r: string} | string | function> | Optional list with custom rules
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### Returns
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Type | Description
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---- | -----------
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Node | Returns the simplified form of `expr`
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## Examples
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```js
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math.simplify('2 * 1 * x ^ (2 - 1)'); // Node {2 * x}
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math.simplify('2 * 3 * x', {x: 4}); // Node {24}
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var f = math.parse('2 * 1 * x ^ (2 - 1)');
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math.simplify(f); // Node {2 * x}
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```
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## See also
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[derivative](derivative.md),
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[parse](parse.md),
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[eval](eval.md)
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