1 | // $Id: Linear.cc 675 2006-10-10 12:08:45Z jari $ |
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2 | |
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3 | /* |
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4 | Copyright (C) The authors contributing to this file. |
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5 | |
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6 | This file is part of the yat library, http://lev.thep.lu.se/trac/yat |
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7 | |
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8 | The yat library is free software; you can redistribute it and/or |
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9 | modify it under the terms of the GNU General Public License as |
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10 | published by the Free Software Foundation; either version 2 of the |
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11 | License, or (at your option) any later version. |
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12 | |
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13 | The yat library is distributed in the hope that it will be useful, |
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14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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16 | General Public License for more details. |
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17 | |
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18 | You should have received a copy of the GNU General Public License |
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19 | along with this program; if not, write to the Free Software |
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20 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA |
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21 | 02111-1307, USA. |
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22 | */ |
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23 | |
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24 | #include "yat/statistics/Linear.h" |
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25 | |
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26 | #include "yat/statistics/AveragerPair.h" |
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27 | #include "yat/utility/vector.h" |
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28 | |
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29 | #include <gsl/gsl_fit.h> |
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30 | |
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31 | |
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32 | namespace theplu { |
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33 | namespace statistics { |
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34 | namespace regression { |
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35 | |
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36 | |
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37 | void Linear::fit(const utility::vector& x, const utility::vector& y) |
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38 | { |
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39 | ap_.reset(); |
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40 | for (size_t i=0; i<x.size(); i++) |
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41 | ap_.add(x(i),y(i)); |
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42 | |
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43 | alpha_ = ap_.y_averager().mean(); |
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44 | beta_ = ap_.covariance() / ap_.x_averager().variance(); |
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45 | |
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46 | // calculating deviation between data and model |
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47 | msd_ = (ap_.y_averager().sum_xx_centered() - ap_.sum_xy_centered() * |
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48 | ap_.sum_xy_centered()/ap_.x_averager().sum_xx_centered() )/x.size(); |
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49 | r2_= 1-msd_/ap_.x_averager().variance(); |
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50 | alpha_var_ = msd_ / x.size(); |
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51 | beta_var_ = msd_ / ap_.x_averager().sum_xx_centered(); |
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52 | m_x_ = ap_.x_averager().mean(); |
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53 | } |
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54 | |
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55 | double Linear::predict(const double x) const |
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56 | { |
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57 | return alpha_ + beta_ * (x-m_x_); |
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58 | } |
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59 | |
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60 | double Linear::prediction_error(const double x) const |
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61 | { |
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62 | return sqrt( alpha_var_+beta_var_*(x-m_x_)*(x-m_x_)+msd_ ); |
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63 | } |
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64 | |
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65 | double Linear::standard_error(const double x) const |
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66 | { |
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67 | return sqrt( alpha_var_+beta_var_*(x-m_x_)*(x-m_x_)); |
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68 | } |
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69 | |
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70 | }}} // of namespaces regression, statisitcs and thep |
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