When you construct a Decimal from a floating-point number, you get the exact value of the floating-point number, which may not precisely match the decimal value because that’s how floating-point numbers work. If you want to do precise decimal arithmetic, construct your Decimal objects from strings instead of floating-point numbers: >>> Decimal(‘22.0’) / Decimal(‘10.0’) – … Read more
cout << fixed << setprecision(2) << total; setprecision specifies the minimum precision. So cout << setprecision (2) << 1.2; will print 1.2 fixed says that there will be a fixed number of decimal digits after the decimal point cout << setprecision (2) << fixed << 1.2; will print 1.20
For the listed code, you can use np.isclose and with it tolerance values could be specified too. Using the provided sample, let’s see how it could be used – In [201]: n = 10 …: m = 4 …: …: tag = np.random.rand(n, m) …: …: s1 = np.sum(tag, axis=1) …: s2 = np.sum(tag[:, ::-1], … Read more
You need to understand something: 100.55 is a decimal number (presented in decimal radix). 100.55 in decimal is a finite number and is exactly this: 100.55. Computers in general store numbers in binary representation. The number 100.55 cannot be represented with a finite binary number: 100.55 is an infinite number in binary representation (same reason … Read more
Use the decimal data type. “The Decimal value type is appropriate for financial calculations requiring large numbers of significant integral and fractional digits and no round-off errors.”
The Boost.Multiprecision library has a decimal based floating point template class called cpp_dec_float, for which you can specify any precision you want. #include <iostream> #include <iomanip> #include <boost/multiprecision/cpp_dec_float.hpp> int main() { namespace mp = boost::multiprecision; // here I’m using a predefined type that stores 100 digits, // but you can create custom types very easily … Read more
There are functions available for doing exactly that, but they can depend on what language you use. Two examples: if you have access to a decent C99 math library, you can use nextafter (and its float and long double variants, nextafterf and nextafterl); or the nexttoward family (which take a long double as second argument). … Read more
Use the “R” numeric format string: double d = 0.00034101243963859839; string s = d.ToString(“R”); //… double d2 = double.Parse(s); if(d == d2) { //– Success } The R stands for “round-trip”. From the linked document: This format is supported only for the Single and Double types. The round-trip specifier guarantees that a numeric value converted … Read more