round.cpp

round.cpp

#ifdef __SHELL__
set -ex
if [ "$0" = "sh" ]; then
  curl https://gist.githubusercontent.com/fclairamb/0387016387c5474e06476f0a84b6ad86/raw/round.cpp > round.cpp && \
  chmod a+rx round.cpp && \
  ./round.cpp
  exit $?
fi

BIN=test-$(arch)
if [ "$FLAGS" = "" ]; then
  FLAGS="-ffast-math -ffp-contract=fast -O3"
fi
g++ $FLAGS $0 -o $BIN
./$BIN 
exit $?
#endif

#include <stdio.h>
void example_1() {
  printf("Example 1:\n");
  double x = 50178230318.0;
  double y = 100000000000.0;
  double ratio = x/y;
  printf("x/y  = %18.18f\n", ratio);
}

#include <cstdlib>
#include <iostream>
#include <cmath>

double round(double v, double digit)
{
    double pow = std::pow(10.0, digit);
    double t = v * pow;
    //std::cout << "t:" << t << std::endl;
    double r = std::floor(t + 0.5);
    //std::cout << "r:" << r << std::endl;
    return r / pow;
}

void example_2() {
    std::cout << "Example 2:" << std::endl;
    std::cout << round(4.45, 1) << std::endl;
    std::cout << round(4.55, 1) << std::endl;
}

int main(int argc, char **argv) {
  example_1();
  example_2();
}

round.py

#!/usr/bin/env python3

from shapely.geometry import LineString

line1 = LineString([(3726.17, -181.848), (3726.19, -181.794)])
line2 = LineString([(3726.18, -181.729), (3726.25, -182.435)])
point = line1.intersection(line2)
print(point, point.is_valid)

Run it with:

curl https://gist.githubusercontent.com/fclairamb/0387016387c5474e06476f0a84b6ad86/raw/round.cpp | sh
curl https://gist.githubusercontent.com/fclairamb/0387016387c5474e06476f0a84b6ad86/raw/round.py | python3