Actually AFAIK the A10-4600M does do double-precision. The previous generation (Llano series, i.e. 3000 series APUs) did not do double-precision but the new Trinity series does double-precision at 1/16th the speed of single-precision.
As for Radeon 7970M, it does do double precision. Specifications (http://www.amd.com/us/products/notebook/graphics/7000m/7900m/Pages/radeon-7900m-series.aspx#2) the peak is 136 GFlops for double-precision for 7970M.
Obviously i didn't research 7970M enough, but the information on A10-4600M is greatly appreciated.