stdnumericlimitsdoubleinfinity

stdnumericlimitsdoubleinfinity refers to the representation of positive and negative infinity for the double-precision floating-point type as defined in the C++ Standard Library. The numeric_limits class template in the <limits> header provides a way to query properties of arithmetic types. For floating-point types like double, these properties include special values such as infinity.

Positive infinity is typically obtained when a floating-point operation results in a value that is too large to be represented by the double type, or through explicit representation like `std::numeric_limits<double>::infinity()`. Similarly, negative infinity is produced by operations resulting in a value too small (large negative) or through `std::numeric_limits<double>::has_infinity` being true and negative infinity being representable.

The IEEE 754 standard for floating-point arithmetic, which is widely implemented by modern hardware, defines specific bit patterns for positive and negative infinity. In C++, these values can be accessed through `std::numeric_limits<double>::infinity()` for positive infinity. The concept of negative infinity is also supported. Checking for these special values is often done using `std::isinf()` from the <cmath> header.

Operations involving infinity have defined behaviors. For instance, adding a finite number to infinity results in infinity. However, indeterminate forms like infinity minus infinity or zero times infinity result in NaN (Not a Number). Understanding these behaviors is crucial for robust numerical programming.