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133 lines
2.2 KiB
Markdown
133 lines
2.2 KiB
Markdown
---
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title: "standard_deviation"
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---
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{{< callout type="info">}}
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Header: `standard_deviation.h`
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From: `20.9.0`
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{{< /callout >}}
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```cpp
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template <bool Standard_Deviation_Type, typename TInput, typename TCalc = TInput>
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class standard_deviation : public etl::unary_function<TInput, void>
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```
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`Standard_Deviation_Type` `Population` or `Sample`.
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`TInput` The input data type.
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`TCalc` The type to use for internal calculations. By default, equal to `TInput`.
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**Enumeration**
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```cpp
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standard_deviation_type
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etl::standard_deviation_type::Sample
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etl::standard_deviation_type::Population
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```
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---
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```cp
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standard_deviation()
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```
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**Description**
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Default constructor.
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---
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```cpp
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template <typename TIterator>
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standard_deviation(TIterator first, TIterator last)
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```
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**Description**
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Construct from an iterator range.
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---
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```cpp
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void add(TInput value1)
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```
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**Description**
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Add a value.
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---
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```cpp
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template <typename TIterator>
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void add(TIterator first, TIterator last)
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```
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**Description**
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Add a range of values.
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---
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```cpp
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void operator()(TInput value)
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```
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**Description**
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Add a values.
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---
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```cpp
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template <typename TIterator>
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void operator()(TIterator first, TIterator last)
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```
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**Description**
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Add a range of values.
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---
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```cpp
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double get_standard_deviation() const
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```
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**Return**
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The calculated standard deviation for the data.
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---
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```cpp
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double get_variance() const
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```
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**Return**
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The calculated variance for the data.
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---
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```cpp
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operator double() const
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```
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**Return**
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The calculated standard deviation for the data.
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---
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```cpp
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size_t count() const
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```
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**Description**
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Get the total number added entries.
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---
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```cpp
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void clear()
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```
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**Description**
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Clear the standard deviation.
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## Example
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```cpp
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std::array<char, 10> input
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{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9
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};
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etl::standard_deviation<etl::standard_deviation_type::Population, char, int32_t>
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standard_deviation(input.begin(), input.end());
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double standard_deviation_result;
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double variance_result;
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standard_deviation_result = standard_deviation; // standard_deviation_result == 2.87
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variance_result = standard_deviation.get_variance(); // variance_result == 8.25
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```
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