template<typename T>
class lsst::geom::polynomials::SafeSum< T >
A numerically stable summation algorithm for floating-point numbers.
SafeSum implements += and -= operators that can be used to accumulate floating point numbers with very different magnitudes, with accuracy limited only by the usual floating-point inaccuracy in represented the final sum.
SafeSum is explicitly convertible to and from its underlying floating-point type and only supports in-place addition and subtraction, in order to avoid cases where a combination of implicit conversion and multiple overloaded operators could lead to accidental use of regular floating-point operations.
SafeSum uses the Kahan-Neumaier algorithm (though this should be considered an implementation detail by callers), which maintains a lower-order-bit correction that compensates for the loss of precision in the main sum. Particularly aggressive compiler optimizations that do not preserve IEEE floating point behavior (e.g. gcc's -fassociative-math
) may optimize away the correction and reduce SafeSum's behavior to a standard unsafe sum.
Definition at line 62 of file SafeSum.h.