#include #include namespace SL { double const GR = (1 + std::sqrt(5))/2.0; //golden_ratio // calculates the number of fibonacci numbers in a given range. //Input error checking is not done :( int Calfibonum(double const& rfibo){ int nfib=log10(rfibo)/log10(SL::GR); double calfibo=0.0; //calculated fibo // if this step is not done than the result may be wrong due to precision loss. //Usually 1 or 2 iterations are good enough to arrive at correct result while(calfibo <= rfibo) { calfibo = floor(0.5 + std::pow(SL::GR,++nfib)/std::sqrt(5));} return nfib-1; }} int main() { // The upper bound is inclusive std::cout << "Fibonacci numbers in (0-9999999999999999999999999):\t" << SL::Calfibonum(9999999999999999999999999.0) << "\n"; std::cout << "Fibonacci numbers in (0-40):\t" << SL::Calfibonum(40) << "\n"; std::cout << "Fibonacci numbers in (0-55):\t" << SL::Calfibonum(55) << "\n"; std::cout << "Fibonacci numbers in (0-88):\t" << SL::Calfibonum(88) << "\n"; std::cout << "Fibonacci numbers in (0-89):\t" << SL::Calfibonum(89) << "\n"; std::cout << "Fibonacci numbers in (0-6765):\t" << SL::Calfibonum(6765) << "\n"; std::cout << "Fibonacci numbers in (0-6764):\t" << SL::Calfibonum(6764) << "\n"; std::cout << "Fibonacci numbers in (0-75024):\t" << SL::Calfibonum(75024) << "\n"; std::cout << "Fibonacci numbers in (0-75025):\t" << SL::Calfibonum(75025) << "\n"; std::cout << "Fibonacci numbers in (0-75026):\t" << SL::Calfibonum(75026) << "\n"; return 0; }

num_fibonacci.cpp