TIP #299: Add isqrt() Math Function
_____________________________________________________________________________
TIP:	299
Title:	Add isqrt() Math Function
Version:	$Revision: 1.3 $
Authors:	Kevin B. Kenny <kennykb@acm.org>
State:	Final
Type:	Project
Tcl-Version:	8.5
Vote:	Done
Created:	Fri Nov 24 00:00:00 UTC 2006
Keywords:	Tcl, expression, integer, square root
Abstract
This TIP proposes a new expr math function isqrt().
Background
With the advent of large integers, Tcl supports taking the square roots of arguments that lie outside the native floating-point range of the machine. The square roots are returned as floating point numbers if possible. This behaviour is correct when floating-point calculations are intended. There are times, however, when an arbitrary-precision square root is wanted. This root cannot be obtained by evaluating entier(sqrt($n)), because sqrt($n) has already lost precision.
Proposed Change
This TIP proposes adding a new math function, isqrt($n), that will return the integer part of the square root of $n to arbitrary precision. The argument $n must be numeric and non-negative; it may be either integer or floating-point.
Reference Implementation
Tcl Feature Request #1602534 contains a complete reference implementation for the isqrt function.
Copyright
This document has been placed in the public domain.
_____________________________________________________________________________
Colophon
TIP AutoGenerator - written by Donal K. Fellows