61 lines
1.1 KiB
C
61 lines
1.1 KiB
C
#include "linear.h"
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#include <stdlib.h>
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long point_v[1024] = {0};
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long point_l[1024] = {0};
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int point_cnt = 0;
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double k = 0;
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double b = 0;
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double theory_point[1024] = {0};
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double linearity = 0;
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extern double fabs(double __x);
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/// <LinearFit>
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/// 利用两点法进行线性拟合 y = kx + b,
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/// <x,y—存放长度与电压的数组>
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void linear_fit()
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{
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// Ax+By+C=0
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double A = 0;
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double B = 0;
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double C = 0;
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int m = point_cnt;
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A = point_v[m - 1] - point_v[0];
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B = point_l[0] - point_l[m-1];
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C = point_l[m - 1] * point_v[0] - point_l[0] * point_v[m - 1];
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k = -(A / B);
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b = -(C / B);
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}
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/// <summary>
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/// 更新数组y，替换为电压理论值
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void linear_val()
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{
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for (int i = 0; i < point_cnt; i++)
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{
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theory_point[i] = k * point_l[i] + b;
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}
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}
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void get_linearity()
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{
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double max_bias = 0;
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linear_fit();
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linear_val();
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for (int i = 0; i < point_cnt; i++)
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{
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if(fabs(max_bias) < fabs(point_v[i] - theory_point[i]))
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{
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max_bias = point_v[i] - theory_point[i];
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}
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}
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linearity = fabs(max_bias / (point_v[point_cnt-1] - point_v[0]));
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}
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