TIP #299: Add isqrt() Math Function


TIP:299
Title:Add isqrt() Math Function
Version:$Revision: 1.3 $
Author:Kevin B. Kenny <kennykb at acm dot org>
State:Final
Type:Project
Tcl-Version:8.5
Vote:Done
Created:Friday, 24 November 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.


Powered by Tcl[Index] [History] [HTML Format] [Source Format] [LaTeX Format] [Text Format] [XML Format] [*roff Format (experimental)] [RTF Format (experimental)]

TIP AutoGenerator - written by Donal K. Fellows