# Calculate values: the calculator

The Calculator is a service that enables incoming data to be **transformed, recalculated, and aggregated**. For example, values can be converted from watts to kilowatts by dividing them by 1000 upon receipt. The converted value is then displayed in the corresponding attribute in which the calculation was performed.

## Examples

### Convert values

* Watts to kW: 

  ```calculatorLang
  {value}/1000
  ```
* Degrees Celsius to degrees Fahrenheit \[F=(1.8×C)+32]

  ```calculatorLang
  (1.8*{value})+32
  ```

### Calculate new values

* Calculate comfort based on formulas

  ```calculatorLang
  (0.8 * {temperature}) + (0.2 * {humidity})
  ```
* Add People Counter

  ```calculatorLang
  [10.input.count] + [11.input.count] + [12.input.count]
  ```
* Add consumption of multiple meters

  ```calculatorLang
  [10.input.power] + [11.input.power] + [12.input.power]
  ```
* Value is between 1 and 80, then status "0 = Ok" otherwise "1 = Alarm" 

  ```calculatorLang
  not(inrange(1, {value}, 80))
  ```
* Turn heating on or off based on temperature (map 0 to "off", map 1 to "on")

  ```calculatorLang
  {temperature} < 20 ? 1 : 0
  ```

### Syntax

To perform calculations with attributes, put the names of the attributes in curly braces. This allows access to the values of these attributes.

**Access to attributes within an asset**

You can directly access the values of attributes that are of the same type. For example:

```
{temperature} + {humidity}
```

**Access to attributes of different types within an asset**

If you want to access attributes of different types within the same asset, use the following syntax:

* `{input.temperature}`: Access to the "temperature" attribute of the input type
* `{status.temperature}`: Access to the "temperature" attribute of the status type
* `{output.temperature}`: Access to the "temperature" attribute of the output type

**Access to attributes from other assets**

To access the values of attributes from other assets, use the following syntax:

```plaintext
[asset_id.attribute_type.attribute_name]
```

**Example**

```plaintext
[10.input.power] + [11.input.power] + [12.input.power]
```

In this example, the values of the "power" attribute of assets with IDs 10, 11, and 12 are added together.

## Perform calculations

You can perform calculations with attributes in 2 places in Eliona:

* In the asset template
* In the individual asset

Standard calculations are defined in the asset template and are applied to all assets created with this template. However, these calculations can be overridden individually in the individual assets if required.

{% hint style="info" %}
Avoid accessing attributes of other assets in the asset template, because if these change it will lead to problems and all calculations would have to be recreated.
{% endhint %}

### Performing a calculation in an asset template

<figure><img src="/files/c8d58a9ebd6e8ad83bc810ed21fb4722c39853a8" alt=""><figcaption></figcaption></figure>

1. Open an existing asset template or create a new asset template
2. Open an existing attribute or create a new attribute
3. You can **\[A]** perform calculations in the field. These calculations then apply to all assets of this type, but can also be overridden in the individual asset.

### Performing a calculation in an asset

<figure><img src="/files/80e55b3085f9d3575d757a2c120d5ca71850b690" alt=""><figcaption></figcaption></figure>

1. Open the [↗ Asset details](/collection/english-v14/documentation/assets/asset-details.md)
2. Click on the attribute whose values you want to calculate. ▷ The sidebar **\[A]** opens
3. Enter the desired value into the field **\[B]** your calculation.
4. Click on **Save \[X]**

#### Use attributes of another asset (foreign values) in a calculation

This functionality is only possible if you perform calculations in an asset.

1. Open the [↗ Asset details](/collection/english-v14/documentation/assets/asset-details.md)
2. Click on the attribute whose values you want to calculate. ▷ The sidebar **\[A]** opens
3. Enter the desired value into the field **\[B]** your calculation.
4. Click on **\[C1]**, to select the asset whose values you want to use in the calculation.
5. Click on **\[C3]**, to specify the subtype of the asset.
6. Click on **\[C4]**, to specify the attribute you want to use.
7. Click on **\[C5]**, to confirm your selection. ▷ The details now appear in square brackets in field **\[B]**
8. If you want to include additional foreign values in the calculation: 8.1. Click on **\[C2]** 8.2. Repeat steps 4 to 8
9. Click on **Save \[X]**

### **Reset output attribute**

If an **output attribute** is selected, there is the option to reset the value.

* When **clicking on "Reset attribute"** a **zero is written to the attribute**.
* This corresponds to the state as if **no data were stored in the heap**.

<div align="left"><figure><img src="/files/324823060b42d664521c5c02771fce91fcfd9d93" alt="" width="375"><figcaption></figcaption></figure></div>

### Calculation chains

**Calculation chains are created automatically,** when you create calculations, both within an asset and across multiple assets. A calculation chain exists when, for example, "Asset A depends on a value from Asset B, Asset B depends on a value from Asset C, and Asset C depends on a value from Asset D."

Whenever a value in Asset A used in Asset B changes, a calculation is triggered for Asset B. Any change to a value in Asset B referenced in Asset C results in a calculation in Asset C.

The chain is **broken**, if a step of the **calculation fails or does not pass the** [**Filter**](/collection/english-v14/documentation/more-functions/attribute-functions/filter.md) **.** This reduces the number of events in the system.

### Operators and functions

The available operators and functions are listed here.

**Operators**

| Group      | Operators                                                         |
| ---------- | ----------------------------------------------------------------- |
| Arithmetic | +, -, \*, /, % (modulus operator), ^ (exponent)                   |
| Comparison | ==, !=, <, >, <=, >=                                              |
| Logical    | not or !, and or &&, or or                                        |
| Condition  | ? (ternary operator - condition ? value if true : value if false) |

**Features**

Functions can be used in the syntax avg({value1},{value2},{value3})

<table><thead><tr><th width="202">Function</th><th>Description</th></tr></thead><tbody><tr><td>avg</td><td>Returns the average of a list of values (any number of float values)</td></tr><tr><td>max</td><td>Returns the maximum value of a list of values (any number of float values)</td></tr><tr><td>min</td><td>Returns the minimum value of a list of values (any number of float values)</td></tr><tr><td>abs</td><td>Returns the absolute value of a value (single float)</td></tr><tr><td>round</td><td>Rounds a value to the nearest whole number (single float)</td></tr><tr><td>pow</td><td>Exponentiation (2 arguments, the 2nd is the power)</td></tr><tr><td>sin</td><td>Sine of a value in radians</td></tr><tr><td>cos</td><td>Cosine of a value in radians</td></tr><tr><td>cosh</td><td>Hyperbolic cosine of a value in radians</td></tr><tr><td>cot</td><td>Cotangent of a value in radians</td></tr><tr><td>csc</td><td>Cosecant of a value in radians</td></tr><tr><td>sec</td><td>Secant of a value in radians</td></tr><tr><td>equal</td><td>Compares two numbers with a tolerance of 0.001</td></tr><tr><td>not</td><td>Inverts a boolean value</td></tr><tr><td>rad2deg</td><td>Converts radians to degrees</td></tr><tr><td>deg2rad</td><td>Converts degrees to radians</td></tr><tr><td>inrange</td><td>Checks whether a value is within a range (left boundary, value, right boundary)</td></tr><tr><td>history(reference, back_step)</td><td>Returns a historical value of an attribute. <code>reference</code> is the normal reference of the attribute (e.g. <code>[asset_id.subtype.attribute]</code>), and <code>back_step</code> is a negative number indicating which value from the history you want to retrieve. Example: <code>-1</code> returns the previous value, <code>-2</code> the one before that.</td></tr></tbody></table>

These functions and operators enable a wide variety of calculations and logical operations in your calculations.


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