| 1 | /* -*- mode: C; c-basic-offset: 2; indent-tabs-mode: nil; -*- */ |
|---|---|
| 2 | |
| 3 | #include <math.h> |
| 4 | #include "variable.h" |
| 5 | |
| 6 | void |
| 7 | variable_init (Variable *variable) |
| 8 | { |
| 9 | variable->weight = 0.0; |
| 10 | variable->sum = 0.0; |
| 11 | variable->sum2 = 0.0; |
| 12 | } |
| 13 | |
| 14 | void |
| 15 | variable_add_weighted (Variable *variable, |
| 16 | double value, |
| 17 | double weight) |
| 18 | { |
| 19 | variable->weight += weight; |
| 20 | variable->sum += weight * value; |
| 21 | variable->sum2 += weight * value * value; |
| 22 | } |
| 23 | |
| 24 | void |
| 25 | variable_add (Variable *variable, |
| 26 | double value) |
| 27 | { |
| 28 | variable_add_weighted (variable, value, weight: 1.); |
| 29 | } |
| 30 | |
| 31 | double |
| 32 | variable_mean (Variable *variable) |
| 33 | { |
| 34 | return variable->sum / variable->weight; |
| 35 | } |
| 36 | |
| 37 | double |
| 38 | variable_standard_deviation (Variable *variable) |
| 39 | { |
| 40 | double mean = variable_mean (variable); |
| 41 | return sqrt (x: variable->sum2 / variable->weight - mean * mean); |
| 42 | } |
| 43 |