John Gustafson’s crusade to replace floating point with something better
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Re: John Gustafson’s crusade to replace floating point with something better
#2This is awesome. Doubling performance for free sounds good to me.
Re: John Gustafson’s crusade to replace floating point with something better
#3The paper for this was published in 2017[0]
Re: John Gustafson’s crusade to replace floating point with something better
#4Here is the official site[1] of the project. There is a request[2] to add it in the Scryer Prolog[3] (ISO Prolog implementation in Rust). And implementations in Rust[4] itself, and Julia[5] language.
[1] https://posithub.org/index
[2] https://github.com/mthom/scryer-prolog/issues/6
[3] https://github.com/mthom/scryer-prolog
Re: John Gustafson’s crusade to replace floating point with something better
#5Obviously for any 32 bit value there’s only 2^32 possible values. So logically, a better number format is all about the distribution of values and reducing redundancy.
It sounds like the basic idea here is that rather than a fixed amount of significant figures, you get more precision in the middle. Meanwhile, you can also get larger exponents. Is that right?
Re: John Gustafson’s crusade to replace floating point with something better
#6The paper for this was published in 2017[0] [0] https://dl.acm.org/citation.cfm?id=3148220
It's odd. Someone told me about that on irc at the Time. People were feeling strongly about the topic. Quackery, mythomany,.. nobody wanted to hear about anything but IEEE standards.
Re: John Gustafson’s crusade to replace floating point with something better
#7How does the implementation of an FPU for this compare? I thought the existing IEEE 754 floating point standard was focused on reduced complexity of addition and multiplication hardware. This seems more complicated.
Re: John Gustafson’s crusade to replace floating point with something better
#8[deleted]
Re: John Gustafson’s crusade to replace floating point with something better
#9Obviously for any 32 bit value there’s only 2^32 possible values. So logically, a better number format is all about the distribution of values and reducing redundancy. It sounds like the basic idea here is that rather than a fixed amount of significant figures, you get more precision in the middle. Meanwhile, you can also get larger exponents. Is that right?
The ideas are (1) gradual instead of hard overflow [IEEE floats do gradual underflow via denormals], (2) crowding representable numbers more precisely around 1 while letting very large or very small numbers get less and less precise, vs. floating point which (except for denormals) is scale free within its range, (3) making a format which can be extended by just adding bits without new definitions, so that you can get more or less precise numbers as needed by just adding zeros or truncating, (4) a it more uniform logic for basic arithmetic with fewer edge cases.
It's a bit sad that many of the creator’s claims are exaggerated and his examples cherry-picked though.
Re: John Gustafson’s crusade to replace floating point with something better
#10Obviously for any 32 bit value there’s only 2^32 possible values. So logically, a better number format is all about the distribution of values and reducing redundancy. It sounds like the basic idea here is that rather than a fixed amount of significant figures, you get more precision in the middle. Meanwhile, you can also get larger exponents. Is that right?
I agree with your analysis, think utf-8 on ieee754’s exponent.