標題: 最小二乘法擬合一條直線（C語言代碼） [打印本頁]
作者: jialinx    時間: 2015-9-15 14:58
標題: 最小二乘法擬合一條直線（C語言代碼）
  1. #include<stdio.h>


  4. #define N10             //N為要擬合的數據的個數

  6. float X[10] = {1.9,0.8,1.1,0.1,-0.1,4.4,4.6,1.6,5.5,3.4};
  7. float Y[10] = {0.7,-1.0,-0.2,-1.2,-0.1,3.4,0.0,0.8,3.7,2.0};


  10. floatK=0;               //擬合直線的斜率

  12. floatR=0;               //擬合直線的截距

  14. float x_sum_average=0;   //數組 X[N] 個元素求和 并求平均值

  16. float y_sum_average=0;   //數組 Y[N] 個元素求和 并求平均值

  18. float x_square_sum=0;    //數組 X[N] 個個元素的平均值

  20. float x_multiply_y=0;    //數組 X[N]和Y[N]對應元素的乘機

  22. float Squre_sum(float c[N]) ;
  23. float Sum_Average(float d[N]);
  24. float X_Y_By(float m[N],float n[N]);
  25. float Squre_sum(float c[N]);
  26. void Line_Fit(void);


  29. void Line_Fit(void)
  30. {
  31.   x_sum_average= Sum_Average(X);

  33.   y_sum_average= Sum_Average(Y);

  35.   x_square_sum = Squre_sum(X);

  37.   x_multiply_y = X_Y_By(X,Y);

  39.   K = ( x_multiply_y - N * x_sum_average * y_sum_average)/(x_square_sum - N * x_sum_average*x_sum_average );

  41.   R = y_sum_average - K * x_sum_average;

  43.   printf("K = %f\n",K);

  45.   printf("R = %f\n",R);

  47. }



  51. float Sum_Average(float d[N])
  52. {

  54. unsigned int i=0;

  56. float z=0;

  58. for(i=0;i<N;i++)

  60. {
  61. z = z + d[i];
  62. }

  64. z = z/N;

  66. return z;

  68. }

  70. float X_Y_By(float m[N],float n[N])
  71. {

  73. unsigned int i=0;

  75. float z=0;

  77. for(i=0;i<N;i++)

  79. {

  81. z = z + m[i]*n[i];

  83. }

  85. return z;

  87. }



  91. float Squre_sum(float c[N])
  92. {

  94. unsigned int i=0;

  96. float z=0;

  98. for(i=0;i<N;i++)

  100. {

  102. z = z + c[i]*c[i];

  104. }

  106. return z;

  108. }


  111. void main(void)
  112. {

  114.     Line_Fit();

  116. }
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