Add support for frexp() function

[Linyou]

Does taichi has native support for frexp() function？ The documention does not contain any info about frexp.

frexp() is a function that breaks a value into two components which are mantissa and exponent.

[victoriacity]

LLVM seems to have frexp() function, but indeed frexp() is not implemented in the Taichi frontend. @neozhaoliang do you think it would be worth adding to ti.Math module?

[bobcao3]

ref: In SPIR-V there is FrexpStruct. In metal there is frexp

[neozhaoliang]

I think it's good to have this function.

[Linyou]

Thanks for the great work!

[Lithaca]

I am interested in this issue and want to work on it. I am new to taichi, is there any reference material about how to get start.

[lin-hitonami]

Hi @Lithaca, sorry for the late reply. I've looked into the issue and I found that it is a bit hard to add it directly to the IR because it returns two numbers. However, we can write a Taichi function instead to do the same thing. We can add the function to our math module. Here is a possible implementation of frexp written in Java. Here is the documentation of Taichi. Welcome to contribute to our codebase if you are still interested.

[ailzhang]

FYI #7721 added support for CUDA backend, will send out a separate PR for spirv-based (and maybe CPU) backend in the future (lower pri for now).

[aezyus]

I see this issue is still open, I would love to work on it. Do consider.
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