Paul Berry 9c75527299 glsl 1.30: Fix numerical instabilities in asinh ... The formula we were previously using for asinh: asinh x = ln(x + sqrt(x * x + 1)) is numerically unstable: when x is a large negative value, the quantity x + sqrt(x * x + 1) is a small positive value (on the order of 1/(2|x|)). Since the logarithm function is very sensitive in this range, any error in the computation of the square root manifests as a large error in the result. This patch changes to the equivalent formula: asinh x = sign(x) * ln(abs(x) + sqrt(x * x + 1)) which is only slightly more expensive to compute, and is numerically stable for all x. Fixes piglit tests spec/glsl-1.30/execution/built-in-functions/[fv]s-asinh-*. Reviewed-by: Chad Versace <chad@chad-versace.us> Acked-by: Kenneth Graunke <kenneth@whitecape.org> Reviewed-by: Eric Anholt <eric@anholt.net>		2011-09-28 12:20:25 -07:00
..
ir	glsl 1.30: Fix numerical instabilities in asinh	2011-09-28 12:20:25 -07:00
profiles	glsl/builtins: Uncomment textureSize prototypes.	2011-08-23 11:18:03 -07:00
tools	glsl: Defer initialization of built-in functions until they're needed.	2011-09-23 17:12:47 -07:00