rlnorm.h

Go to the documentation of this file.

// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 4 -*-
//
// rlnorm.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_rlnorm_h
#define Rcpp__stats__random_rlnorm_h

namespace Rcpp {
        namespace stats {

                class LNormGenerator : public Generator<false,double> {
                public:
        
                        LNormGenerator( double meanlog_ = 0.0 , double sdlog_ = 1.0 ) : 
                                meanlog(meanlog_), sdlog(sdlog_) {}
        
                        inline double operator()() const {
                                return ::exp( meanlog + sdlog * ::norm_rand() ) ;
                        }
        
                private:
                        double meanlog ;
                        double sdlog ;
                } ;

                class LNormGenerator_1 : public Generator<false,double> {
                public:
        
                        LNormGenerator_1( double meanlog_ = 0.0 ) : 
                                meanlog(meanlog_) {}
        
                        inline double operator()() const {
                                return ::exp( meanlog + ::norm_rand() ) ;
                        }
        
                private:
                        double meanlog ;
                } ;

                class LNormGenerator_0 : public Generator<false,double> {
                public:
        
                        LNormGenerator_0( ) {}
        
                        inline double operator()() const {
                                return ::exp(::norm_rand() ) ;
                        }
        
                } ;

        } // 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 rlnorm( int n, double meanlog, double sdlog ){
                if (ISNAN(meanlog) || !R_FINITE(sdlog) || sdlog < 0.){
                        // TODO: R also throws a warning in that case, should we ?
                        return NumericVector( n, R_NaN ) ;
                }  else if (sdlog == 0. || !R_FINITE(meanlog)){
                        return NumericVector( n, ::exp( meanlog ) ) ;
                } else {
                        return NumericVector( n, stats::LNormGenerator( meanlog, sdlog ) ); 
                }
        }

        // 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 rlnorm( int n, double meanlog /*, double sdlog = 1.0 */){
                if (ISNAN(meanlog) ){
                        // TODO: R also throws a warning in that case, should we ?
                        return NumericVector( n, R_NaN ) ;
                }  else if ( !R_FINITE(meanlog)){
                        return NumericVector( n, ::exp( meanlog ) ) ;
                } else {
                        return NumericVector( n, stats::LNormGenerator_1( meanlog ) ); 
                }
        }

        // 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 rlnorm( int n /*, double meanlog [=0.], double sdlog = 1.0 */){
                return NumericVector( n, stats::LNormGenerator_0( ) ); 
        }


} // Rcpp

#endif