# monoidal product in widening representation
The interval between E and A is a fifth, but it’s upside down, because we’re going down a fifth from E. In music theory terms, an upside down fifth is called a fourth. You go up a fourth by multiplying your frequency by 4/3 (it’s 3/2 upside down, doubled to bring it up an octave.) So your A string is now tuned to 4/3 Hz.
，详情可参考新收录的资料
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Please, please, please stop using passkeys for encrypting user dataFebruary 27, 2026·670 words·4 mins
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Pick Q3 if you want the smallest footprint / best memory savings。新收录的资料是该领域的重要参考
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