My use case may be a little simple, but why is there not an unsigned float type in any language? It seems like positive real numbers is a useful subtype for many engineering problems? Are unsigned ints only done for performance reasons? edit: related to following stack overflow post …

The stackoverflow post you linked is pretty good already. [image] djsegal: not an unsigned float type in any language Because there’s no hardware support and no standard for it. [image] djsegal: useful subtype for many engineering problems Is it? What problems do you have in mind? Wh…

[image] yuyichao: (and there was a very recent thread about it here) Could you link that thread please?

[image] Range checking / bounds (of a variable) checking General Usage Hello, In my old memories, I recall that Ada (programming language) provide a concept of “range” for checking that a numerical value stored in a variable is always between a lower bound and…

[image] yuyichao: [image] djsegal: not an unsigned float type in any language Because there’s no hardware support and no standard for it. That used to be the case, and while I think no standard (yet) I believe there’s Chinese hardware with UE8M0 already (and supported by Nvidia in PTX…

Hmph, isn’t UE8M0 just rebranding integer arithmetic? As in, couldn’t they take the same Int8 circuits from a MOS 6502, and call them the new floating point? No they’re not trolling, it’s literally supported by NVIDIA and used by DeepSeek! Ironic because I could have been a BASIC programmer in the …

[image] apo383: isn’t UE8M0 just rebranding integer arithmetic? As in, couldn’t they take the same Int8 circuits from a MOS 6502, and call them the new floating point? No, not exactly and note (Signed and) Unsigned Julia abstract type do assume integers, and all integers in a range (and 2’s c…

[image] Palli: I assume but haven’t confirmed that you can represent 0 You cannot, the valid range is 2^{−127} to 2^{128}. Source: UE8M0 FP8 Number Format • luminary.blog NVidia is using 0xFF as special value for NaN, which reduces the range to 2^{−127} to 2^{127}.

[image] apo383: couldn’t they take the same Int8 circuits from a MOS 6502, and call them the new floating point? No: the Int8 circuit will compute 0x2 + 0x2 = 0x4, but in UE8M0 0x2 is 4, and 0x2 + 0x2 should return 0x3 (2^3 = 8).

[image] Palli: how Julia should support or adapt… This is too specific to fit into Julia’s generic scientific programming setup (the precision-speed trade-offs are quite extreme), and in any case we are talking about shifting a calculation into logarithms, a very old trick. Even in the ML con…

[image] Palli: UE8M0 … still floating point reals, e.g. 1, 2, 4, 8 They may represent reals but they’re just bits manipulated like integers, just as with all floating point exponents. I was just amused because this is way less than true floating point. In fixed point, addition is easy, and th…

I don’t mean Julia should support this as with Float16, I mean does Julia need an UReal abstract type only (to enable the rest in a package, and better to have the abstract type in Base, as most others)? That’s a really cheap addition. Or does standard Real (abstract type) not really care if negativ…

Why is there no concept of unsigned floats?

General Usage

yuyichao August 26, 2018, 1:34am 4

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Why is there no concept of unsigned floats?

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