線性函數，C語言方式實現
GitHub倉庫：https://github.com/XinLiGH/LinearFunction
PS：博文不再更新，後續更新會在GitHub倉庫進行。
線性函數，C語言方式實現。程序中涉及到線性函數的概念，詳細介紹見維基百科[Linear function](https://en.wikipedia.org/wiki/Linear_function)。
1，開發環境
1，操作系統：Windows 10 專業版
2，IDE：Visual Studio 2017 專業版
2，程序源碼
LinearFunction.h文件
/**
******************************************************************************
* @file LinearFunction.h
* @author XinLi
* @version v1.0
* @date 13-September-2018
* @brief Header file for LinearFunction.c module.
******************************************************************************
* @attention
*
* <h2><center>Copyright © 2018 XinLi</center></h2>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
******************************************************************************
*/
#ifndef __LINEARFUNCTION_H
#define __LINEARFUNCTION_H
#ifdef __cplusplus
extern "C" {
#endif
/* Header includes -----------------------------------------------------------*/
/* Macro definitions ---------------------------------------------------------*/
/* Type definitions ----------------------------------------------------------*/
typedef struct
{
float slope;
float intercept;
}LinearFunction;
/* Variable declarations -----------------------------------------------------*/
/* Variable definitions ------------------------------------------------------*/
/* Function declarations -----------------------------------------------------*/
void LinearFunction_PointSlopeInit(LinearFunction *function, float x, float y, float slope);
void LinearFunction_TwoPointInit(LinearFunction *function, float x1, float y1, float x2, float y2);
void LinearFunction_SetSlope(LinearFunction *function, float slope);
void LinearFunction_SetIntercept(LinearFunction *function, float intercept);
float LinearFunction_GetSlope(LinearFunction *function);
float LinearFunction_GetIntercept(LinearFunction *function);
float LinearFunction_GetAbscissa(LinearFunction *function, float y);
float LinearFunction_GetOrdinate(LinearFunction *function, float x);
float LinearFunction_PointToPointDistance(float x1, float y1, float x2, float y2);
float LinearFunction_PointToLineDistance(LinearFunction *function, float x, float y);
float LinearFunction_LineToLineDistance(LinearFunction *function1, LinearFunction *function2);
float LinearFunction_TwoLineAngle(LinearFunction *function1, LinearFunction *function2);
/* Function definitions ------------------------------------------------------*/
#ifdef __cplusplus
}
#endif
#endif /* __LINEARFUNCTION_H */
LinearFunction.c文件
/**
******************************************************************************
* @file LinearFunction.c
* @author XinLi
* @version v1.0
* @date 13-September-2018
* @brief Linear function module source file.
******************************************************************************
* @attention
*
* <h2><center>Copyright © 2018 XinLi</center></h2>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
******************************************************************************
*/
/* Header includes -----------------------------------------------------------*/
#include "LinearFunction.h"
#include <math.h>
/* Macro definitions ---------------------------------------------------------*/
/* Type definitions ----------------------------------------------------------*/
/* Variable declarations -----------------------------------------------------*/
/* Variable definitions ------------------------------------------------------*/
/* Function declarations -----------------------------------------------------*/
/* Function definitions ------------------------------------------------------*/
/**
* @brief Linear function point slope initialize.
* @param [in] function: Linear function data type.
* @param [in] x: The abscissa of the point.
* @param [in] y: The ordinate of the point.
* @param [in] slope: Linear function slope.
* @return None.
*/
void LinearFunction_PointSlopeInit(LinearFunction *function, float x, float y, float slope)
{
function->slope = slope;
function->intercept = y - x * slope;
}
/**
* @brief Linear function two point initialize.
* @param [in] function: Linear function data type.
* @param [in] x1: The abscissa of the point.
* @param [in] y1: The ordinate of the point.
* @param [in] x2: The abscissa of the point.
* @param [in] y2: The ordinate of the point.
* @return None.
*/
void LinearFunction_TwoPointInit(LinearFunction *function, float x1, float y1, float x2, float y2)
{
function->slope = (y2 - y1) / (x2 - x1);
function->intercept = y1 - x1 * (y2 - y1) / (x2 - x1);
}
/**
* @brief Linear function set slope.
* @param [in] function: Linear function data type.
* @param [in] slope: Linear function slope.
* @return None.
*/
void LinearFunction_SetSlope(LinearFunction *function, float slope)
{
function->slope = slope;
}
/**
* @brief Linear function set intercept.
* @param [in] function: Linear function data type.
* @param [in] intercept: Linear function intercept.
* @return None.
*/
void LinearFunction_SetIntercept(LinearFunction *function, float intercept)
{
function->intercept = intercept;
}
/**
* @brief Linear function get slope.
* @param [in] function: Linear function data type.
* @return Linear function slope.
*/
float LinearFunction_GetSlope(LinearFunction *function)
{
return function->slope;
}
/**
* @brief Linear function get intercept.
* @param [in] function: Linear function data type.
* @return Linear function intercept.
*/
float LinearFunction_GetIntercept(LinearFunction *function)
{
return function->intercept;
}
/**
* @brief Linear function get abscissa.
* @param [in] function: Linear function data type.
* @param [in] y: The ordinate of the point on the linear function.
* @return The abscissa of the point on the linear function.
*/
float LinearFunction_GetAbscissa(LinearFunction *function, float y)
{
return (y - function->intercept) / function->slope;
}
/**
* @brief Linear function get ordinate.
* @param [in] function: Linear function data type.
* @param [in] x: The abscissa of the point on the linear function.
* @return The ordinate of the point on the linear function.
*/
float LinearFunction_GetOrdinate(LinearFunction *function, float x)
{
return function->slope * x + function->intercept;
}
/**
* @brief Point to point distance.
* @param [in] x1: The abscissa of the point.
* @param [in] y1: The ordinate of the point.
* @param [in] x2: The abscissa of the point.
* @param [in] y2: The ordinate of the point.
* @return Point to point distance.
*/
float LinearFunction_PointToPointDistance(float x1, float y1, float x2, float y2)
{
return hypotf(x1 - x2, y1 - y2);
}
/**
* @brief Point to line distance.
* @param [in] function: Linear function data type.
* @param [in] x: The abscissa of the point.
* @param [in] y: The ordinate of the point.
* @return Point to line distance.
*/
float LinearFunction_PointToLineDistance(LinearFunction *function, float x, float y)
{
return fabsf(function->slope * x - y + function->intercept) / hypotf(function->slope, -1.0f);
}
/**
* @brief Line to line distance.
* @param [in] function1: Linear function data type.
* @param [in] function2: Linear function data type.
* @return Line to line distance.
*/
float LinearFunction_LineToLineDistance(LinearFunction *function1, LinearFunction *function2)
{
if(function1->slope == function2->slope)
{
return fabsf(function1->intercept - function2->intercept) / hypotf(function1->slope, -1.0f);
}
else
{
return 0.0f;
}
}
/**
* @brief Two line angle.
* @param [in] function1: Linear function data type.
* @param [in] function2: Linear function data type.
* @return Two line angle, unit: rad.
*/
float LinearFunction_TwoLineAngle(LinearFunction *function1, LinearFunction *function2)
{
return acosf(fabsf(function1->slope * function2->slope + 1.0f) / (hypotf(function1->slope, -1.0f) * hypotf(function2->slope, -1.0f)));
}
main.c文件
/**
******************************************************************************
* @file main.c
* @author XinLi
* @version v1.0
* @date 13-September-2018
* @brief Main program body.
******************************************************************************
* @attention
*
* <h2><center>Copyright © 2018 XinLi</center></h2>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
******************************************************************************
*/
/* Header includes -----------------------------------------------------------*/
#include "LinearFunction.h"
#include <stdio.h>
#include <windows.h>
/* Macro definitions ---------------------------------------------------------*/
/* Type definitions ----------------------------------------------------------*/
typedef struct
{
float x;
float y;
}Point;
/* Variable declarations -----------------------------------------------------*/
/* Variable definitions ------------------------------------------------------*/
/* Function declarations -----------------------------------------------------*/
/* Function definitions ------------------------------------------------------*/
/**
* @brief Main program.
* @param None.
* @return None.
*/
int main(void)
{
for(;;)
{
Point pointA = {.x = 2.5f, .y = 3.4f};
Point pointB = {.x = 5.6f, .y = 4.3f};
Point pointC = {.x = 7.8f, .y = 1.5f};
Point pointD = {.x = 4.6f};
Point pointE = {.y = 9.7f};
LinearFunction lineAB = {0};
LinearFunction lineAC = {0};
LinearFunction lineCD = {0};
LinearFunction_TwoPointInit(&lineAB, pointA.x, pointA.y, pointB.x, pointB.y);
LinearFunction_TwoPointInit(&lineAC, pointA.x, pointA.y, pointC.x, pointC.y);
LinearFunction_PointSlopeInit(&lineCD, pointC.x, pointC.y, LinearFunction_GetSlope(&lineAB));
pointD.y = LinearFunction_GetOrdinate(&lineCD, pointD.x);
pointE.x = LinearFunction_GetAbscissa(&lineAC, pointE.y);
printf("A(%f, %f)\t", pointA.x, pointA.y);
printf("B(%f, %f)\t", pointB.x, pointB.y);
printf("C(%f, %f)\t", pointC.x, pointC.y);
printf("D(%f, %f)\t", pointD.x, pointD.y);
printf("E(%f, %f)\n", pointE.x, pointE.y);
printf("AB(y = %fx + %f)\t", LinearFunction_GetSlope(&lineAB), LinearFunction_GetIntercept(&lineAB));
printf("AC(y = %fx + %f)\t", LinearFunction_GetSlope(&lineAC), LinearFunction_GetIntercept(&lineAC));
printf("CD(y = %fx - %f)\n", LinearFunction_GetSlope(&lineCD), LinearFunction_GetIntercept(&lineCD) * (-1.0f));
printf("|AB| = %f\t", LinearFunction_PointToPointDistance(pointA.x, pointA.y, pointB.x, pointB.y));
printf("∠BAC = %f rad\n", LinearFunction_TwoLineAngle(&lineAB, &lineAC));
printf("點 E 到直線 AB 的距離等於 %f\n", LinearFunction_PointToLineDistance(&lineAB, pointE.x, pointE.y));
printf("直線 AB 到直線 CD 的距離等於 %f\n\n", LinearFunction_LineToLineDistance(&lineAB, &lineCD));
Sleep(5000);
}
}
3，運行效果
