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linear_regression.c
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linear_regression.c
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/*
* linear_regression.c
*
* Created on: Apr 20, 2024
* Author: alexei.guriev
*/
/*==================================================================================================
* INCLUDE FILES
==================================================================================================*/
#include "linear_regression.h"
#include <stdio.h>
#include <stdlib.h>
/*==================================================================================================
* LOCAL MACROS
==================================================================================================*/
/*==================================================================================================
* LOCAL TYPEDEFS (STRUCTURES, UNIONS, ENUMS)
==================================================================================================*/
/*==================================================================================================
* GLOBAL VARIABLES
==================================================================================================*/
/*==================================================================================================
* LOCAL VARIABLES
==================================================================================================*/
/*==================================================================================================
* LOCAL FUNCTION PROTOTYPES
==================================================================================================*/
/*==================================================================================================
* GLOBAL FUNCTIONS
==================================================================================================*/
/**
* @brief LinearRegression calc
*
* @param[in] dataX X buffer data.
* @param[in] dataY Y buffer data.
* @param[in] n elements number
*
* @return Linear Regression result: NULL - wrong data; Not NULL - calc data
*/
LinearRegressionResult* LinearRegression(double *dataX, double *dataY, int n)
{
if (dataX == NULL || dataY == NULL || n <= 0)
{
return NULL;
}
double sum_x = 0, sum_y = 0, sum_xy = 0, sum_x_squared = 0;
for (int i = 0; i < n; i++)
{
sum_x += dataX[i];
sum_y += dataY[i];
sum_xy += dataX[i] * dataY[i];
sum_x_squared += dataX[i] * dataX[i];
}
double mean_x = sum_x / n;
double mean_y = sum_y / n;
double slope = (sum_xy - n * mean_x * mean_y) / (sum_x_squared - n * mean_x * mean_x);
double intercept = mean_y - slope * mean_x;
LinearRegressionResult* result = malloc(sizeof(LinearRegressionResult));
if (result == NULL)
{
return NULL;
}
result->slope = slope;
result->intercept = intercept;
return result;
}
/*==================================================================================================
* LOCAL FUNCTIONS
==================================================================================================*/