rnorm.h

Go to the documentation of this file.

// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 4 -*-
//
// rnorm.h: Rcpp R/C++ interface class library -- 
//
// Copyright (C) 2010 - 2011 Douglas Bates, Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// Rcpp is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.

#ifndef Rcpp__stats__random_rnorm_h
#define Rcpp__stats__random_rnorm_h

namespace Rcpp {
        namespace stats {

                class NormGenerator : public Generator<false,double> {
                public:
        
                        NormGenerator( double mean_ = 0.0 , double sd_ = 1.0 ) : 
                                mean(mean_), sd(sd_) {}
        
                        inline double operator()() const {
                                return mean + sd * ::norm_rand() ;
                        }
        
                private:
                        double mean ;
                        double sd ;
                } ;


                class NormGenerator__sd1 : public Generator<false,double> {
                public:
        
                        NormGenerator__sd1( double mean_ = 0.0 ) : mean(mean_) {}
        
                        inline double operator()() const {
                                return mean + ::norm_rand() ;
                        }
        
                private:
                        double mean ;
                } ;


                class NormGenerator__mean0 : public Generator<false,double> {
                public:
        
                        NormGenerator__mean0( double sd_ = 1.0 ) : sd(sd_) {}
        
                        inline double operator()() const {
                                return sd * ::norm_rand() ;
                        }
        
                private:
                        double sd ;
                } ;


        } // stats

        // Please make sure you to read Section 6.3 of "Writing R Extensions"
        // about the need to call GetRNGstate() and PutRNGstate() when using 
        // the random number generators provided by R.
        inline NumericVector rnorm( int n, double mean, double sd){
                if (ISNAN(mean) || !R_FINITE(sd) || sd < 0.){
                        // TODO: R also throws a warning in that case, should we ?
                        return NumericVector( n, R_NaN ) ;
                }  else if (sd == 0. || !R_FINITE(mean)){
                        return NumericVector( n, mean ) ;
                } else {
                        bool sd1 = sd == 1.0 ; 
                        bool mean0 = mean == 0.0 ;
                        if( sd1 && mean0 ){
                                return NumericVector( n, norm_rand ) ;
                        } else if( sd1 ){
                                return NumericVector( n, stats::NormGenerator__sd1( mean ) );
                        } else if( mean0 ){
                                return NumericVector( n, stats::NormGenerator__mean0( sd ) );
                        } else {
                                // general case
                                return NumericVector( n, stats::NormGenerator( mean, sd ) );
                        }
                }
        }

        // Please make sure you to read Section 6.3 of "Writing R Extensions"
        // about the need to call GetRNGstate() and PutRNGstate() when using 
        // the random number generators provided by R.
        inline NumericVector rnorm( int n, double mean /*, double sd [=1.0] */ ){
                if (ISNAN(mean) ){
                        // TODO: R also throws a warning in that case, should we ?
                        return NumericVector( n, R_NaN ) ;
                }  else if ( !R_FINITE(mean)){
                        return NumericVector( n, mean ) ;
                } else {
                        bool mean0 = mean == 0.0 ;
                        if( mean0 ){
                                return NumericVector( n, norm_rand ) ;
                        } else {
                                return NumericVector( n, stats::NormGenerator__sd1( mean ) );
                        }
                }
        }

        // Please make sure you to read Section 6.3 of "Writing R Extensions"
        // about the need to call GetRNGstate() and PutRNGstate() when using 
        // the random number generators provided by R.
        inline NumericVector rnorm( int n /*, double mean [=0.0], double sd [=1.0] */ ){
                return NumericVector( n, norm_rand ) ;
        }

} // Rcpp

#endif