I forwarded your latest reply, Bill, to the friend of mine who introduced me to the new NVIDIA graphics card, Forrest H Bennett III. His reply seems worth posting here, so I do so now:
- - - Bill makes good points, here are some things to keep in mind. First of all, nVidia is releasing a double precision GPU this year. Second, GPUs change much faster than CPUs. The GPU used in the Fay et al paper, the GeForce 7300 GT (G73), is already a generation old. If you look at nVidia's current generation GPU, the GeForce 8800 (G80), you find that the IEEE 754 compliance has already improved. According to these specs, most of the issues raised by the Fay et al paper have already been addressed: "Special encodings for NaN (not a number), +/-INF (infinity), and positive and negative zero are supported. Denorms (values less than 2^-126, which have an exponent encoding of "0" and no implied leading one) are supported, but may be flushed to zero, preserving the sign bit of the original value. Arithmetic operations are carried out at single-precision using normal IEEE floating-point rules, including special rules for generating infinities, NaNs, and zeros of each sign." http://developer.download.nvidia.com/opengl/specs/g80specs.pdf "Its primary ALU structure is fully FP32 and completely meets IEEE754 standards for computation and rounding of single precision floats, and supports most '754 specials other than denorm signalling and propogation." http://www.cnblogs.com/wangdaniu/archive/2006/11/09/555004.html IEEE 754 also requires 5 exceptions and 4 rounding modes, and I cannot verify that the 8800 supports any of these other than the default rounding mode. Since most programming languages don't support anything but the default rounding mode anyway - I don't see that as an issue. The architecture of the 8800 is far more general than previously seen in a GPU. It is the second GPU for which a non graphics related SDK has been released by the hardware vendor. ____________________________________________________________________________________ Do you Yahoo!? Everyone is raving about the all-new Yahoo! Mail beta. http://new.mail.yahoo.com ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
