double                 package:base                 R Documentation

Double Precision Vectors

Description:

     Create, coerce to or test for a double-precision vector.

Usage:

     double(length = 0)
     as.double(x, ...)
     is.double(x)

     single(length = 0)
     as.single(x, ...)

Arguments:

  length: desired length.

       x: object to be coerced or tested.

     ...: further arguments passed to or from other methods.

Value:

     'double' creates a double precision vector of the specified
     length.  The elements of the vector are all equal to '0'.

     'as.double' attempts to coerce its argument to be of double type:
     like 'as.vector' it strips attributes including names.  Character
     strings containing either a decimal representation or a
     heaxadecimal representation (starting with '0x' or '0X') can be
     converted.

     'is.double' returns 'TRUE' or 'FALSE' depending on whether its
     argument is of double type or not.  It is generic: you can write
     methods to handle specific classes of objects, see
     InternalMethods.

Note:

     _R has no single precision data type.  All real numbers are stored
     in double precision format_.  The functions 'as.single' and
     'single' are identical to 'as.double' and 'double' except they set
     the attribute 'Csingle' that is used in the '.C' and '.Fortran'
     interface, and they are intended only to be used in that context.

References:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

See Also:

     'integer', 'numeric'.

Examples:

     is.double(1)
     all(double(3) == 0)

