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nodes/math/expression/README.md

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+---
+hide_title: true
+hide_table_of_contents: true
+title: Expression
+---
+
+<##head##>
+
+# Expression
+
+This node enables you to do your own calculations using simple expressons. Inputs are automatically derived from the expression. An expression set to `a + someName + 1` will get two inputs: one for <span className="ndl-data">a</span> and one for <span className="ndl-data">someName</span>.
+
+<div className="ndl-image-with-background xl">
+
+![](/nodes/math/expression/expression-1.png)
+
+</div>
+
+The <span className="ndl-node">Expression</span> node runs JavaScript under the hood and supports a range of mathematical expressions.
+
+<##head##>
+
+## Built in math functions
+
+Expressions support the following funcitons:
+
+-   `min(a,b)` - Minimum of two values
+-   `max(a,b)` - Maximum of two values
+-   `cos(angle)` - The cosine of an angle in radians
+-   `sin(angle)` - The sine of an angle in radians
+-   `tan(angle)` - The tangent of an angle in radians
+-   `sqrt(a)` - Square root of a number
+-   `pi` - PI in radians
+-   `round(a)` - Rounds a number to the closest integer
+-   `floor(a)` - Removes the fractional part of a number
+-   `ceil(a)` - Rounds a value up to the closest higher integer. E.g. `round(1.1)` equals `2`.
+-   `abs(a)` - The absolute value of a number. Negative values will become positive.
+-   `random()` - A random number from 0 to 1
+
+## Advanced
+
+The _Expression_ node is running JavaScript under the hood so in addition to the above functions any standard
+JavaScript functions will also be valid. The _Expression_ node will add a `return` statement before the
+expression is executed. `1+2` will be evaluated as `return (1+2)`
+
+## Truthy and Falsy signals
+
+You can use the signal outputs <span className="ndl-signal">On True</span> and <span className="ndl-signal">On False</span> to trigger actions based on the result of an expression, if the result is considered "truthy" or "falsy" in Javascript.
+
+Normally, an expression node recalculates whenever one of the input parameters change. However, if you connect a signal to the <span className="ndl-signal">Run</span> signal input you can control when the expression is calculated. It will only calculate and update it's outputs when a signal is received.
+
+<div className="ndl-image-with-background xl">
+
+![](/nodes/math/expression/expression-2.png)
+
+</div>
+
+## Inputs
+
+| Data                                         | Description                                                                                                                                                                                                                                |
+| -------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| <span className="ndl-data">Expression</span> | The expression to be calculated.  |
+| <span className="ndl-data">Run</span> | Normally the expression is recalucated every time one of the input parameters change. But if you want to control when the expression is calculated you can connect a signal to this input, then the expression will **only** be calculated when a signal is received.  |
+
+
+### Parameters
+Inputs are automatically derived from the expression. An expression set to `a + someName + 1` will get two inputs, one for `a` and one for `someName`.<br/><br/>As soon as any of the input values changes, the expression is reevaluated. 
+
+## Outputs
+
+| Data                                     | Description                                                                                   |
+| ---------------------------------------- | --------------------------------------------------------------------------------------------- |
+| <span className="ndl-data">Result</span> | <##output:result##>This output contains the result when evaluating the expression<##output##> |
+| <span className="ndl-data">Is true</span> | <##output:isTrue##>This output will be true if the result of the expression is "truthy", that is considered true in Javascript.<##output##> |
+| <span className="ndl-data">Is false</span> | <##output:isFalse##>This output will be true if the result of the expression is "falsy", that is considered false in Javascript.<##output##> |
+| <span className="ndl-signal">On True</span> | <##output:isTrueEv##>A signal will be sent on this output when the expression is calculated and the result is "truthy".<##output##> |
+| <span className="ndl-signal">On False</span> | <##output:isFalseEv##>A signal will be sent on this output when the expression is calculated and the result is "falsy".<##output##> |
+
+