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Matrix Multiplication Inches Closer To Mythic Goal

quantamagazine.org

1–10 of 53 posts

Re: Matrix Multiplication Inches Closer To Mythic Goal

#2
Fun article. The approach to n^2.

> The result, by Josh Alman, a postdoctoral researcher at Harvard University, and Virginia Vassilevska Williams of the Massachusetts Institute of Technology, shaves about one-hundred-thousandth off the exponent of the previous best mark. It’s typical of the recent painstaking gains in the field.

Re: Matrix Multiplication Inches Closer To Mythic Goal

#6

Which one of these algos does Intel/Nvidia/Google use in their AVX/Cuda/TPU implementations?

Simple block partitioning, usually 4x4, with the full ordinary algorithm per block. This is the most numerically-stable and parallel.

https://developer.nvidia.com/blog/cutlass-linear-algebra-cud...

Re: Matrix Multiplication Inches Closer To Mythic Goal

#8
post #7
post #5

Earlier quoted context omitted.

Strassen's method is the only one practical on modern hardware

And only in fixed precision.

What makes you say that? I've had good speedups with Strassen multiplication in variable precision (or with floating-point, in case you meant fixed-point arithmetic).

Re: Matrix Multiplication Inches Closer To Mythic Goal

#9
post #8
post #7

Earlier quoted context omitted.

And only in fixed precision.

What makes you say that? I've had good speedups with Strassen multiplication in variable precision (or with floating-point, in case you meant fixed-point arithmetic).

Strassen method is faster than native multiplication, but it is not stable: you will get much larger rounding errors when implementing it using floating point numbers, compared to native multipllication. And fine precision is required for a lot of algorithm implemented using matrix multiplication, such as matrix inversion or gradient descent, so this is often a problem.

Re: Matrix Multiplication Inches Closer To Mythic Goal

#10
post #8
post #7

Earlier quoted context omitted.

And only in fixed precision.

What makes you say that? I've had good speedups with Strassen multiplication in variable precision (or with floating-point, in case you meant fixed-point arithmetic).

Speed is fine. The issue is numerical stability.
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