From 8a458bbf5bc6fcfa66d6e96e0dea1ec20b2fd0d9 Mon Sep 17 00:00:00 2001 From: Bjørn Lindeijer Date: Sun, 16 Nov 2008 16:21:37 +0100 Subject: Got rid of CVS/Subversion $Id$ markers I don't know why we dealt with these things for so long. Did we ever get anything out of it? --- src/utils/fastsqrt.h | 50 ++++++++++++++++++++++++-------------------------- 1 file changed, 24 insertions(+), 26 deletions(-) (limited to 'src/utils/fastsqrt.h') diff --git a/src/utils/fastsqrt.h b/src/utils/fastsqrt.h index afadb901..78768149 100644 --- a/src/utils/fastsqrt.h +++ b/src/utils/fastsqrt.h @@ -1,26 +1,24 @@ -/* A very fast function to calculate the approximate inverse square root of a - * floating point value and a helper function that uses it for getting the - * normal squareroot. For an explanation of the inverse squareroot function - * read: - * http://www.math.purdue.edu/~clomont/Math/Papers/2003/InvSqrt.pdf - * - * Unfortunately the original creator of this function seems to be unknown. - * - * $Id$ - */ - -float fastInvSqrt(float x) -{ - union { int i; float x; } tmp; - float xhalf = 0.5f * x; - tmp.x = x; - tmp.i = 0x5f375a86 - (tmp.i >> 1); - x = tmp.x; - x = x * (1.5f - xhalf * x * x); - return x; -} - -float fastSqrt(float x) -{ - return 1.0f / fastInvSqrt(x); -} +/* A very fast function to calculate the approximate inverse square root of a + * floating point value and a helper function that uses it for getting the + * normal squareroot. For an explanation of the inverse squareroot function + * read: + * http://www.math.purdue.edu/~clomont/Math/Papers/2003/InvSqrt.pdf + * + * Unfortunately the original creator of this function seems to be unknown. + */ + +float fastInvSqrt(float x) +{ + union { int i; float x; } tmp; + float xhalf = 0.5f * x; + tmp.x = x; + tmp.i = 0x5f375a86 - (tmp.i >> 1); + x = tmp.x; + x = x * (1.5f - xhalf * x * x); + return x; +} + +float fastSqrt(float x) +{ + return 1.0f / fastInvSqrt(x); +} -- cgit v1.2.3-60-g2f50