Originally posted by sandy8925
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Linus Torvalds: "I Hope AVX512 Dies A Painful Death"
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Originally posted by zyxxel View Post
How would you compute sqrt(17) with 1000 decimals using your double variables? You are basically making a statement that is as intelligent as saying that it's glue you use as fuel for your car.
Floating point is named as it is, because it has a mantissa and an exponent  and a floating point register is designed to store an *approximation* of a number. In some specific cases, it manages to store the exact value. Most times, not.
Integer arithmetic  as in fixed point  can handle the value 1.33333934565634382349214134124185194999911 exactly. No round off. No unexpected "accident".
In many situation, it's impossible to use floating point just because of the reverse of your claim  the floating point registers can't maintain the precision needed. They can't store the exact values. And if you have a very numerically sensitive algorithm, it may explode from the lack of precision.
Ever wondered why the world has big number libraries, when we already know how large values you can fit in a 64bit or maybe 80bit floating point register?
https://blogs.mathworks.com/cleve/20...ntarithmetic/
Of course big numbers libraries do exist for a reason, but integer like fixed point has so few usages if you know quad precision, that it is essentially pointless.
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Originally posted by piotrj3 View Post
Sorry to tell you that, but there are solutions for double being not precize enough. It is mostly known as triple/quad precision and it is not even that hard to implement.
https://blogs.mathworks.com/cleve/20...ntarithmetic/
Of course big numbers libraries do exist for a reason, but integer like fixed point has so few usages if you know quad precision, that it is essentially pointless.
Quad precision doesn't get you very far. It has eps 1.9259e34
That is rather far away from a thousand decimals. 1000 decimal digits is over 3000 bits.
It's quite few situations where double precision is too small while quad precision is enough. Most of the time, you either manage with float/double or you need really much more  and correct  digits.
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Originally posted by Paradigm Shifter View PostTo get AVX512, you need either a modern Xeon, or their HEDT chips. [...] It is essentially impossible to put together a system for testing AVX512 utility without putting down quite a chunk of change
Code:$ tr '\040' '\012' < /proc/cpuinfo  sort fu  fgrep i avx avx avx2 avx512_bitalg avx512bw avx512cd avx512dq avx512f avx512ifma avx512vbmi avx512_vbmi2 avx512vl avx512_vnni avx512_vpopcntdq
AVX512 is also a random grabbag of confusion  and it is "one" set of instruction set extensions!
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Originally posted by kcrudup View PostNot sure if this is covered in a later comment but I don't consider the i71065G7 IceLake CPU in my laptop all that special, but FWIW:
This. I have no idea what all those AVX512 variants mean or differentiate between another.
https://en.wikipedia.org/wiki/AVX512#CPUs_with_AVX512
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Originally posted by kcrudup View PostNot sure if this is covered in a later comment but I don't consider the i71065G7 IceLake CPU in my laptop all that special, but FWIW:
That said, they're barely fit to set up a testing box. I could compile programs on them, but wouldn't be able to really do anything worthwhile due to core or RAM limits. ;(
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