tesseract 4.1.1
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QLSQ Class Reference

#include <quadlsq.h>

Public Member Functions

 QLSQ ()
 
void clear ()
 
void add (double x, double y)
 
void remove (double x, double y)
 
int32_t count ()
 
void fit (int degree)
 
double get_a ()
 
double get_b ()
 
double get_c ()
 

Detailed Description

Definition at line 25 of file quadlsq.h.

Constructor & Destructor Documentation

◆ QLSQ()

QLSQ::QLSQ ( )
inline

Definition at line 28 of file quadlsq.h.

28 { //constructor
29 clear(); //set to zeros
30 }
void clear()
Definition: quadlsq.cpp:33

Member Function Documentation

◆ add()

void QLSQ::add ( double  x,
double  y 
)

Definition at line 55 of file quadlsq.cpp.

55 {
56 n++; // Count elements.
57 sigx += x; // Update accumulators.
58 sigy += y;
59 sigxx += x * x;
60 sigxy += x * y;
61 sigyy += y * y;
62 sigxxx += static_cast<long double>(x) * x * x;
63 sigxxy += static_cast<long double>(x) * x * y;
64 sigxxxx += static_cast<long double>(x) * x * x * x;
65}

◆ clear()

void QLSQ::clear ( )

Definition at line 33 of file quadlsq.cpp.

33 { // initialize
34 a = 0.0;
35 b = 0.0;
36 c = 0.0;
37 n = 0; // No elements.
38 sigx = 0.0; // Zero accumulators.
39 sigy = 0.0;
40 sigxx = 0.0;
41 sigxy = 0.0;
42 sigyy = 0.0;
43 sigxxx = 0.0;
44 sigxxy = 0.0;
45 sigxxxx = 0.0;
46}

◆ count()

int32_t QLSQ::count ( )
inline

Definition at line 39 of file quadlsq.h.

39 { //no of elements
40 return n;
41 }

◆ fit()

void QLSQ::fit ( int  degree)

Definition at line 99 of file quadlsq.cpp.

99 {
100 long double x_variance = static_cast<long double>(sigxx) * n -
101 static_cast<long double>(sigx) * sigx;
102
103 // Note: for computational efficiency, we do not normalize the variance,
104 // covariance and cube variance here as they are in the same order in both
105 // nominators and denominators. However, we need be careful in value range
106 // check.
107 if (x_variance < kMinVariance * n * n || degree < 1 || n < 2) {
108 // We cannot calculate b reliably so forget a and b, and just work on c.
109 a = b = 0.0;
110 if (n >= 1 && degree >= 0) {
111 c = sigy / n;
112 } else {
113 c = 0.0;
114 }
115 return;
116 }
117 long double top96 = 0.0; // Accurate top.
118 long double bottom96 = 0.0; // Accurate bottom.
119 long double cubevar = sigxxx * n - static_cast<long double>(sigxx) * sigx;
120 long double covariance = static_cast<long double>(sigxy) * n -
121 static_cast<long double>(sigx) * sigy;
122
123 if (n >= 4 && degree >= 2) {
124 top96 = cubevar * covariance;
125 top96 += x_variance * (static_cast<long double>(sigxx) * sigy - sigxxy * n);
126
127 bottom96 = cubevar * cubevar;
128 bottom96 -= x_variance *
129 (sigxxxx * n - static_cast<long double>(sigxx) * sigxx);
130 }
131 if (bottom96 >= kMinVariance * n * n * n * n) {
132 // Denominators looking good
133 a = top96 / bottom96;
134 top96 = covariance - cubevar * a;
135 b = top96 / x_variance;
136 } else {
137 // Forget a, and concentrate on b.
138 a = 0.0;
139 b = covariance / x_variance;
140 }
141 c = (sigy - a * sigxx - b * sigx) / n;
142}
const long double kMinVariance
Definition: quadlsq.cpp:25

◆ get_a()

double QLSQ::get_a ( )
inline

Definition at line 45 of file quadlsq.h.

45 { //get x squard
46 return a;
47 }

◆ get_b()

double QLSQ::get_b ( )
inline

Definition at line 48 of file quadlsq.h.

48 { //get x squard
49 return b;
50 }

◆ get_c()

double QLSQ::get_c ( )
inline

Definition at line 51 of file quadlsq.h.

51 { //get x squard
52 return c;
53 }

◆ remove()

void QLSQ::remove ( double  x,
double  y 
)

Definition at line 74 of file quadlsq.cpp.

74 {
75 if (n <= 0) {
76 tprintf("Can't remove an element from an empty QLSQ accumulator!\n");
77 return;
78 }
79 n--; // Count elements.
80 sigx -= x; // Update accumulators.
81 sigy -= y;
82 sigxx -= x * x;
83 sigxy -= x * y;
84 sigyy -= y * y;
85 sigxxx -= static_cast<long double>(x) * x * x;
86 sigxxy -= static_cast<long double>(x) * x * y;
87 sigxxxx -= static_cast<long double>(x) * x * x * x;
88}
DLLSYM void tprintf(const char *format,...)
Definition: tprintf.cpp:35

The documentation for this class was generated from the following files: