Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!haven!adm!smoke!ibd!heilpern
From: heilpern@ibd.BRL.MIL (Mark A. Heilpern )
Newsgroups: comp.lang.c
Subject: Re: Help needed to round-off a number
Message-ID: <267@ibd.BRL.MIL>
Date: 2 Jun 89 17:47:07 GMT
References: <2666@oregon.uoregon.edu>
Reply-To: heilpern@brl.arpa (Mark A. Heilpern (IBD) <heilpern>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 17

In article <2666@oregon.uoregon.edu> michelbi@oregon.uoregon.edu (Michel Biedermann) writes:
>Is there a C function (user defined or primitive (?)) that will let me
>truncate or round-off a number UP TO a certain decimal place.  For example
>transforming .567 into .6 or -1.502 into -1.5.
> 
>Thanks a lot for the help...
> 

There is a relatively painless way to do this:
1) you want to round off to 'n' places:
2) multiply your original by 10^n
2a) add (5 / 10^n) for round-up error
3) truncate the fraction off of your answer
4) divide this result by 10^n
5) you've just rounded to n decimal places.

	--M.