Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!rpi!batcomputer!cornell!uw-beaver!uw-entropy!dataio!bright
From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.lang.c
Subject: Re: Integer square root routine needed.
Message-ID: <2082@dataio.Data-IO.COM>
Date: 2 Aug 89 17:35:24 GMT
References: <7415@ecsvax.UUCP>
Reply-To: bright@dataio.Data-IO.COM (Walter Bright)
Organization: Data I/O Corporation; Redmond, WA
Lines: 24

In article <7415@ecsvax.UUCP> utoddl@ecsvax.UUCP (Todd M. Lewis) writes:
>This may be the wrong place to post this, but I need C source
>to a reasonably fast integer square root routine.

/***************************
 * Compute the square root using Newton's method.
 * Donated to Public Domain.
 */

unsigned long ulsqrt(l)
unsigned long l;
{	unsigned long c1;

	/* Perhaps we could do better than this for a first guess	*/
	c1 = (l >> 1) + 1;
	while (c1 * c1 > l)
	{
		c1 = (c1 + l / c1) >> 1;
		/*printf("c1 = %ld\n",c1);*/
	}
	return c1;
}

If you can improve on this, please let me know.