[R] how much performance penalty does this incur, scalar as a vector of one element?

Luke Tierney luke at stat.uiowa.edu
Fri Feb 23 16:26:05 CET 2007


Thanks -- that's good to know.

Best,

luke

On Fri, 23 Feb 2007, Jeffrey J. Hallman wrote:

> The 64 bit version of VisualWorks Smalltalk has an immediate ShortDouble,
> which sacrifices two bits of exponent for a tag.  It thus has the same
> precision as an IEEE double, but one fourth as much range.  Overflows
> automatically get promoted to ordinary Double's, which are pointers to objects
> holding real IEEE doubles.
>
> Luke Tierney <luke at stat.uiowa.edu> writes:
>> Systems that
>> support integer scalars often represent them as immediate values within
>> pointers by sacrificing one or two bits of precision in the integers,
>> but that doesn't work for double precision floats except possibly on
>> 64-bit systems.
>
>

-- 
Luke Tierney
Chair, Statistics and Actuarial Science
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:      luke at stat.uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu



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