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58 lines
1.9 KiB
Markdown
58 lines
1.9 KiB
Markdown
---
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title: Doing Math
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---
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# #10. Doing Math
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<div class="ui segment note">
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<span class="ui ribbon label">Note</span>
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This is a web-version of a tutorial chapter embedded right into the XOD IDE.
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To get a better learning experience we recommend to install the
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<a href="/downloads/">desktop IDE</a> or start the
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<a href="/ide/">browser-based IDE</a>, and you’ll see the same tutorial there.
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</div>
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You probably noticed that pins have different colors.
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The pin’s color indicates the *type* of data that this pin is compatible with.
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Green pins can take and return numerical values. Blue pins work with pulses, a
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special data type that we will return to later.
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Let’s try to do some math.
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As you can guess, the `multiply` node transfers the result of the multiplication
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of the numbers from the input pins (`IN1` and `IN2`) to the output pin.
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In `xod/core`, you will find nodes for different mathematical and trigonometric
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calculations. Along with the `multiply` node, you will find `add`, `subtract`,
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and `divide` for very basic computations.
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## Test circuit
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<div class="ui segment note">
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<span class="ui ribbon label">Note</span>
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The circuit is the same as for the previous lesson.
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</div>
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[↓ Download as a Fritzing project](./circuit.fzz)
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## How-to
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1. Add a new `multiply` or another math node to the patch.
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2. Link its left input to the first value provider.
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3. Set the right input value with the Inspector or link it to an output too.
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Turn the potentiometer knob. If you have followed the example. The LED on port
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11 will reach the maximum brightness with a half-turn of the knob. This happens
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because the `multiply` node multiplied the input values and transferred them to
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the `OUT` pin. As `IN2` was set to 2 in the Inspector, the value of the `pot`
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node doubles before reaching the `LUM` pin of LED2.
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[Next lesson →](../11-servo/)
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