1*4882a593Smuzhiyun #include"interpolation.h"
2*4882a593Smuzhiyun #include "math.h"
3*4882a593Smuzhiyun #include <stdlib.h>
4*4882a593Smuzhiyun
interpolation(const float * x,const float * y,int Num,float x0,float * y0)5*4882a593Smuzhiyun void interpolation(const float *x, const float *y, int Num, float x0, float*y0)
6*4882a593Smuzhiyun {
7*4882a593Smuzhiyun int i, index;
8*4882a593Smuzhiyun float k;
9*4882a593Smuzhiyun if (x0 <= x[0])
10*4882a593Smuzhiyun {
11*4882a593Smuzhiyun k = y[0];
12*4882a593Smuzhiyun }
13*4882a593Smuzhiyun else if (x0 >= x[Num - 1])
14*4882a593Smuzhiyun {
15*4882a593Smuzhiyun k = y[Num - 1];
16*4882a593Smuzhiyun }
17*4882a593Smuzhiyun else
18*4882a593Smuzhiyun {
19*4882a593Smuzhiyun for (i = 0; i < Num; i++)
20*4882a593Smuzhiyun {
21*4882a593Smuzhiyun if (x0 < x[i])
22*4882a593Smuzhiyun break;
23*4882a593Smuzhiyun }
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun index = i - 1;
26*4882a593Smuzhiyun if ((float)x[index + 1] - (float)x[index] < 0.001)
27*4882a593Smuzhiyun k = (float)y[index];
28*4882a593Smuzhiyun else
29*4882a593Smuzhiyun k = ((float)x0 - (float)x[index]) / ((float)x[index + 1] - (float)x[index])
30*4882a593Smuzhiyun * ((float)y[index + 1] - (float)y[index])
31*4882a593Smuzhiyun + (float)y[index];
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun *y0 = k;
35*4882a593Smuzhiyun }
36*4882a593Smuzhiyun
interpolation(const float * x,const unsigned short * y,int Num,float x0,unsigned short * y0)37*4882a593Smuzhiyun void interpolation(const float *x, const unsigned short *y, int Num, float x0, unsigned short *y0)
38*4882a593Smuzhiyun {
39*4882a593Smuzhiyun int i, index;
40*4882a593Smuzhiyun float k;
41*4882a593Smuzhiyun if (x0 <= x[0])
42*4882a593Smuzhiyun {
43*4882a593Smuzhiyun k = y[0];
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun else if (x0 >= x[Num - 1])
46*4882a593Smuzhiyun {
47*4882a593Smuzhiyun k = y[Num - 1];
48*4882a593Smuzhiyun }
49*4882a593Smuzhiyun else
50*4882a593Smuzhiyun {
51*4882a593Smuzhiyun for (i = 0; i < Num; i++)
52*4882a593Smuzhiyun {
53*4882a593Smuzhiyun if (x0 < x[i])
54*4882a593Smuzhiyun break;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun index = i - 1;
58*4882a593Smuzhiyun if ((float)x[index + 1] - (float)x[index] < 0.001)
59*4882a593Smuzhiyun k = (float)y[index];
60*4882a593Smuzhiyun else
61*4882a593Smuzhiyun k = ((float)x0 - (float)x[index]) / ((float)x[index + 1] - (float)x[index])
62*4882a593Smuzhiyun * ((float)y[index + 1] - (float)y[index])
63*4882a593Smuzhiyun + (float)y[index];
64*4882a593Smuzhiyun }
65*4882a593Smuzhiyun
66*4882a593Smuzhiyun *y0 = (unsigned short)(k+0.5);
67*4882a593Smuzhiyun }
68*4882a593Smuzhiyun
interpolation(unsigned char * x,bool * y,int xNum,unsigned char x0,bool * y0)69*4882a593Smuzhiyun int interpolation(unsigned char *x, bool *y, int xNum, unsigned char x0, bool *y0)
70*4882a593Smuzhiyun {
71*4882a593Smuzhiyun int i, index;
72*4882a593Smuzhiyun bool k;
73*4882a593Smuzhiyun if (x0 <= x[0] || x0 <= x[1])
74*4882a593Smuzhiyun {
75*4882a593Smuzhiyun k = y[0];
76*4882a593Smuzhiyun index = 0;
77*4882a593Smuzhiyun }
78*4882a593Smuzhiyun else if (x0 >= x[xNum - 1])
79*4882a593Smuzhiyun {
80*4882a593Smuzhiyun k = y[xNum - 2];
81*4882a593Smuzhiyun index = xNum - 2;
82*4882a593Smuzhiyun }
83*4882a593Smuzhiyun else {
84*4882a593Smuzhiyun for (i = 0; i < xNum; i++)
85*4882a593Smuzhiyun {
86*4882a593Smuzhiyun if (x0 < x[i])
87*4882a593Smuzhiyun break;
88*4882a593Smuzhiyun }
89*4882a593Smuzhiyun
90*4882a593Smuzhiyun index = i - 1;
91*4882a593Smuzhiyun if (abs(x[index + 1] - x0) > abs(x0 - x[index])) {
92*4882a593Smuzhiyun k = y[index - 1];
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun else {
95*4882a593Smuzhiyun k = y[index];
96*4882a593Smuzhiyun }
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun *y0 = k;
99*4882a593Smuzhiyun return(index);
100*4882a593Smuzhiyun }
101