Ice Sheet System Model  4.18
Code documentation
GaussianVariogram.cpp
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1 
5 #ifdef HAVE_CONFIG_H
6  #include <config.h>
7 #else
8 #error "Cannot compile with HAVE_CONFIG_H symbol! run configure first!"
9 #endif
10 
11 #include "../classes.h"
12 #include "../../shared/shared.h"
13 
14 /*GaussianVariogram constructors and destructor*/
16  this->nugget = 0.2;
17  this->sill = 1;
18  this->range = SQRT3;
19  return;
20 }
21 /*}}}*/
23 
24  /*Defaults*/
25  this->nugget = 0.2;
26  this->sill = 1;
27  this->range = SQRT3;
28 
29  /*Overwrite from options*/
30  if(options->GetOption("nugget")) options->Get(&this->nugget,"nugget");
31  if(options->GetOption("sill")) options->Get(&this->sill,"sill");
32  if(options->GetOption("range")) options->Get(&this->range,"range");
33 
34  /*Checks*/
35  if(nugget==sill) _error_("nugget and sill cannot be equal (constant semivariogram not allowed)");
36 }
37 /*}}}*/
39  return;
40 }
41 /*}}}*/
42 
43 /*Object virtual functions definitions:*/
45  return new GaussianVariogram(*this);
46 }
47 /*}}}*/
48 void GaussianVariogram::Echo(void){/*{{{*/
49  _printf_("GaussianVariogram\n");
50  _printf_(" nugget: " << this->nugget << "\n");
51  _printf_(" sill : " << this->sill << "\n");
52  _printf_(" range : " << this->range << "\n");
53 }
54 /*}}}*/
55 
56 /*Variogram function*/
57 double GaussianVariogram::Covariance(double deltax,double deltay){/*{{{*/
58  /*The covariance can be deduced from the variogram from the following
59  * relationship:
60  * 2 gamma = C(x,x) + C(y,y) -2 C(x,y)
61  * so
62  * C(h) = sill - gamma */
63  double h2,a,cova;
64 
65  /*Calculate length square*/
66  h2=deltax*deltax + deltay*deltay;
67 
68  /*If h is too small, return sill*/
69  if(h2<0.0000001) return sill;
70 
71  /*compute covariance*/
72  a = 1./3.;
73  cova = (sill-nugget)*exp(-h2/(a*range*range));
74 
75  return cova;
76 }
77 /*}}}*/
78 double GaussianVariogram::SemiVariogram(double deltax,double deltay){/*{{{*/
79  /*http://en.wikipedia.org/wiki/Variogram*/
80  double h2,a,gamma;
81 
82  /*Calculate length square*/
83  h2=deltax*deltax + deltay*deltay;
84 
85  /*return semi-variogram*/
86  a = 1./3.;
87  gamma = (sill-nugget)*(1.-exp(-h2/(a*range*range))) + nugget;
88 
89  //if(h2>1000*1000) _printf_("gamma = " << gamma << " h= " << sqrt(h2) << "\n");
90  _printf_("h = " << sqrt(h2) << " gamma = " << gamma << "\n");
91  return gamma;
92 }
93 /*}}}*/
Options
Definition: Options.h:9
GaussianVariogram::Covariance
double Covariance(double deltax, double deltay)
Definition: GaussianVariogram.cpp:57
_printf_
#define _printf_(StreamArgs)
Definition: Print.h:22
Object
Definition: Object.h:13
GaussianVariogram::sill
double sill
Definition: GaussianVariogram.h:16
Options::Get
void Get(OptionType *pvalue, const char *name)
Definition: Options.h:21
Options::GetOption
Option * GetOption(const char *name)
Definition: Options.cpp:67
_error_
#define _error_(StreamArgs)
Definition: exceptions.h:49
GaussianVariogram::~GaussianVariogram
~GaussianVariogram()
Definition: GaussianVariogram.cpp:38
GaussianVariogram::SemiVariogram
double SemiVariogram(double deltax, double deltay)
Definition: GaussianVariogram.cpp:78
GaussianVariogram::nugget
double nugget
Definition: GaussianVariogram.h:15
GaussianVariogram::copy
Object * copy()
Definition: GaussianVariogram.cpp:44
GaussianVariogram::GaussianVariogram
GaussianVariogram()
Definition: GaussianVariogram.cpp:15
SQRT3
#define SQRT3
Definition: constants.h:10
GaussianVariogram::Echo
void Echo()
Definition: GaussianVariogram.cpp:48
GaussianVariogram::range
double range
Definition: GaussianVariogram.h:17