The most intuitive explanation of floats I've ever come across, courtesy of @fabynou fabiensanglard.net/floating_point…

Nov 7, 2025 · 4:11 PM UTC

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Replying to @GPU_MODE
@GPU_MODE @fabynou now do denormalized
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Replying to @GPU_MODE
@GPU_MODE @fabynou I've never seen a description of exponent and mantissa that isn't just... This. What's different except the names?
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Replying to @GPU_MODE
@GPU_MODE @fabynou But, but, but ... this is the same explanation as always!
He's just decided to use his own names to call what everyone else calls mantissa and exponent.
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Replying to @GPU_MODE
@GPU_MODE @fabynou This maybe correct, but explaining it as a window and an offset has left me completely clueless. It's far more intuitive when explained as a mantissa and exponent.
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Replying to @GPU_MODE
@GPU_MODE @fabynou @grok does this mean that very large floating point numbers close to the ieee limits have lesser precision ?
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Replying to @GPU_MODE
@GPU_MODE @fabynou this intuition model should be presented in every classes that teach floating point numbers
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Replying to @GPU_MODE
@GPU_MODE @fabynou That’s not really why they’re called “floats” tho.

You’re representing N significant digits and where the “radix point” is (we call it a “decimal point” in base 10. IEEE is just one way of historically representing floats, there have been literally hundreds.
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Replying to @GPU_MODE
@GPU_MODE @fabynou This made me feel like that video of vegetarians eating meat for the first time... and crying.
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Replying to @GPU_MODE
@GPU_MODE @fabynou The most intuitive explanation I ever got was an analogy between floating point numbers and ticks on a ruler. The linked explanation is a bog standard explanation. I think I first got it in assembly language programming, again in numerical analysis, & yet again in some PL course.
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Replying to @GPU_MODE
@GPU_MODE @fabynou This is actually great
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Replying to @GPU_MODE
@GPU_MODE @fabynou Very nice. I am 100% going to use this next time I explain floats. Bravo!
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Replying to @GPU_MODE
@GPU_MODE @fabynou Great! So for arbitrary precision, can't we just create a tree of offsets?
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Replying to @GPU_MODE
@GPU_MODEf@fabynou is gold exposes why FP16 denormals vanish at 2⁻¹⁴ but FP32 holds to 2⁻¹²⁶. GPU kernels lean on this: BF16 strips subnormals to save gates, while TF32 uses FP32’s mantissa with FP64’s range for matmul without overflow. Real trick? Hardware fma units fuse before rounding offset reveals the hidden guard bits. 🤯
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Replying to @GPU_MODE
@GPU_MODE @fabynou I've always found floating point numbers to be a bit of a black box. This explanation makes it much more intuitive. Thanks for sharing!
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