[Someone]

That would take way too much room. A full lookup table would have 2^64 entries of 64 bits each, at 2^70 bits of ROM.

For comparison:

- Apple’s M2 Ultra has about 134 billion transistors. That’s about 2^38.

- Avogadro’s number is about 2^79.

Reducing the argument to a small range around zero decreases that a lot, but not enough by a far stretch. There are 2^52 doubles in [0.5, 1.0), 2^52 more in [0.25, 0.5], 2^52 more in [0.125, 0.25], etc. so you’d still easily need 2^52 entries or 2^58 bits (likely way, way more)

[demondemidi]

They DO use a lookup table because that’s what the FDIV but came from:

https://en.m.wikipedia.org/wiki/Pentium_FDIV_bug

“It is implemented using a programmable logic array with 2,048 cells, of which 1,066 cells should have been populated with one of five values: −2, −1, 0, +1, +2.”

Not sure what you’re trying to demonstrate, they wouldn’t store every single float!! I hope don’t program. ;)