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A comment on 0.30000000000000004. Parent comment

Re:0.30000000000000004 by simias on Monday December 02, 2019 @04:52PM (#21687417)
They said floating point decimal types which probably means BCD.
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Re:0.30000000000000004 by recursive on Monday December 02, 2019 @06:19PM (#21688184)
There are different implementations, and BCD is only one of them. Another popular one is a mantissa and exponent, but the exponent is for a 10-based shift rather than the typical floating point.
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Re:0.30000000000000004 by anonydsfsfs on Monday December 02, 2019 @07:23PM (#21688635)
IEEE 754 defines decimal floating point: https://en.wikipedia.org/wiki/Decimal_floating_point#IEEE_75...
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Re:0.30000000000000004 by jhj on Monday December 02, 2019 @11:16PM (#21689876)
Tbey mean radix-10 floating point, as compared to the radix-2 floating point you are thinking of. The packing of the decimal fractional digits in the significand of a radix-10 FP number need not be in BCD, it can use other encodings (e.g., DPD or something else).

0.3 is exactly representable in radix-10 floating point but not radix-2 FP (would be rounded to a maximum of 0.5 ulp error as seen in the title), for instance, just as 1/3 = 0.3333... is exactly representable in radix-3 floating point but neither radix-2 or radix-10 FP, etc.

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