1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
use crate::Result;

/// The `Min` trait specifies than an object has a minimum value
pub trait Min<T> {
    /// Returns the minimum value in the domain of a given distribution
    /// representable by a double-precision float. May panic depending on
    /// the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Min;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.0, n.min());
    /// ```
    fn min(&self) -> T;
}

/// The `Max` trait specifies that an object has a maximum value
pub trait Max<T> {
    /// Returns the maximum value in the domain of a given distribution
    /// representable by a double-precision float. May panic depending on
    /// the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Max;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(1.0, n.max());
    /// ```
    fn max(&self) -> T;
}

/// The `Mean` trait specifies that an object has a closed form
/// solution for its mean(s)
pub trait Mean<T> {
    /// Returns the mean. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Mean;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.5, n.mean());
    /// ```
    fn mean(&self) -> T;
}

/// The `CheckedMean` trait specifies that an object has a closed form
/// solution for its mean(s) with possible failure modes
pub trait CheckedMean<T> {
    /// Returns the mean.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedMean;
    /// use statrs::distribution::FisherSnedecor;
    ///
    /// let n = FisherSnedecor::new(1.0, 1.0).unwrap();
    /// assert!(n.checked_mean().is_err());
    /// ```
    fn checked_mean(&self) -> Result<T>;
}

/// The `Variance` trait specifies that an object has a closed form solution for
/// its variance(s). Requires `Mean` since a closed form solution to
/// variance by definition requires a closed form mean.
pub trait Variance<T>: Mean<T> {
    /// Returns the variance. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Variance;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(1.0 / 12.0, n.variance());
    /// ```
    fn variance(&self) -> T;

    /// Returns the standard deviation. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Variance;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!((1f64 / 12f64).sqrt(), n.std_dev());
    /// ```
    fn std_dev(&self) -> T;
}

pub trait CheckedVariance<T>: CheckedMean<T> {
    /// Returns the variance.
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedVariance;
    /// use statrs::distribution::FisherSnedecor;
    ///
    /// let n = FisherSnedecor::new(1.0, 1.0).unwrap();
    /// assert!(n.checked_variance().is_err());
    /// ```
    fn checked_variance(&self) -> Result<T>;

    /// Returns the standard deviation.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedVariance;
    /// use statrs::distribution::FisherSnedecor;
    ///
    /// let n = FisherSnedecor::new(1.0, 1.0).unwrap();
    /// assert!(n.checked_std_dev().is_err());
    /// ```
    fn checked_std_dev(&self) -> Result<T>;
}

/// The `Entropy` trait specifies an object that has a closed form solution
/// for its entropy
pub trait Entropy<T> {
    /// Returns the entropy. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Entropy;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.0, n.entropy());
    /// ```
    fn entropy(&self) -> T;
}

/// The `CheckedEntropy` trait specifies an object that has a closed form
/// solutions for its entropy wih possible failure modes
pub trait CheckedEntropy<T> {
    /// Returns the entropy.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedEntropy;
    /// use statrs::distribution::StudentsT;
    ///
    /// let n = StudentsT::new(0.0, 2.0, 1.0).unwrap();
    /// assert!(n.checked_entropy().is_err());
    /// ```
    fn checked_entropy(&self) -> Result<T>;
}

/// The `Skewness` trait specifies an object that has a closed form solution
/// for its skewness(s)
pub trait Skewness<T> {
    /// Returns the skewness. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Skewness;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.0, n.skewness());
    /// ```
    fn skewness(&self) -> T;
}

/// The `CheckedSkewness` trait specifies an object that has a closed form
/// solution for its skewness(s) with possible failure modes
pub trait CheckedSkewness<T> {
    /// Returns the skewness.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedSkewness;
    /// use statrs::distribution::FisherSnedecor;
    ///
    /// let n = FisherSnedecor::new(1.0, 1.0).unwrap();
    /// assert!(n.checked_skewness().is_err());
    /// ```
    fn checked_skewness(&self) -> Result<T>;
}

/// The `Median` trait specifies than an object has a closed form solution
/// for its median
pub trait Median<T> {
    /// Returns the median. May panic depending
    /// on the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Median;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.5, n.median());
    /// ```
    fn median(&self) -> T;
}

/// The `Mode` trait specififies that an object has a closed form solution
/// for its mode(s)
pub trait Mode<T> {
    /// Returns the mode. May panic depending on
    /// the implementor.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::Mode;
    /// use statrs::distribution::Uniform;
    ///
    /// let n = Uniform::new(0.0, 1.0).unwrap();
    /// assert_eq!(0.5, n.mode());
    /// ```
    fn mode(&self) -> T;
}

/// The `CheckedMode` trait specifies that an object has a closed form solution
/// for its mode(s) with a possible failure mode
pub trait CheckedMode<T> {
    /// Returns the mode.
    ///
    /// # Examples
    ///
    /// ```
    /// use statrs::statistics::CheckedMode;
    /// use statrs::distribution::Beta;
    ///
    /// let n = Beta::new(1.0, 1.0).unwrap();
    /// assert!(n.checked_mode().is_err());
    /// ```
    fn checked_mode(&self) -> Result<T>;
}