DSIN

dsin is a name used in some programming environments to denote the sine function when operating on double-precision floating-point numbers. It is not a universal standard, and its exact meaning can vary by language, library, or legacy codebase. In many older fortran and C libraries, separate entry points or identifiers existed for different numeric precisions, with dsin commonly representing the double-precision variant of sine.

Historically, dsin originated in contexts where functions were provided with explicit precision indications, such as double precision in Fortran or specialized math libraries. In modern Fortran, the intrinsic SIN function handles real numbers with specified kinds, and explicit separate names like DSIN are less common, but may still appear in older code or vendor-specific libraries.

Common usage and behavior: dsin(X) returns the sine of X, where X is in radians and the result is in the same double-precision format. The mathematical definition is sin(X), with X in radians and the range of the result limited to [-1, 1]. Implementation details typically involve range reduction and polynomial or table-based approximations to balance speed and accuracy. Numerical issues can arise near multiples of pi where cancellation or rounding errors may affect precision.

In other contexts, dsin may simply be a user-defined function or a naming convention used to emphasize double-precision input and output, distinct from single-precision sine variants such as sinf or just sin in languages that unify the precision under a single intrinsic.

See also: sine, trigonometric functions, double precision, Fortran intrinsic functions.