Tenney–Euclidean metrics: Difference between revisions

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The '''Tenney–Euclidean norm''' ('''TE norm''') or '''Tenney–Euclidean complexity''' ('''TE complexity''') applies to vals as well as to monzos.  
The '''Tenney–Euclidean norm''' ('''TE norm''') or '''Tenney–Euclidean complexity''' ('''TE complexity''') applies to vals as well as to monzos.  


Let us define the val weighting matrix ''W'' to be the {{w|diagonal matrix}} with values 1, 1/log<sub>2</sub>3, 1/log<sub>2</sub>5 … 1/log<sub>2</sub>''p'' along the diagonal. Given a val '''a''' expressed as a row vector, the corresponding vector in weighted coordinates is {{nowrap|'''v''' {{=}} '''a'''''W''}}, with transpose {{nowrap|'''v'''{{t}} {{=}} ''W'''''a'''{{t}}}} where {{t}} denotes the transpose. Then the dot product of weighted vals is {{nowrap|'''vv'''{{t}} {{=}} '''a'''''W''&#x200A;<sup>2</sup>'''a'''{{t}}}}, which makes the Euclidean metric on vals, a measure of complexity, to be {{nowrap|‖'''v'''‖<sub>2</sub> {{=}} √('''vv'''{{t}})}} {{nowrap|{{=}} √({{subsup|''a''|2|2}} + {{subsup|''a''|3|2}}/(log<sub>2</sub>3)<sup>2</sup> + … + {{subsup|''a''|''p''|2}}/(log<sub>2</sub>''p'')<sup>2</sup>)}}; dividing this by √(''n''), where {{nowrap|''n'' {{=}} π(''p'')}} is the number of primes to ''p'', gives the TE norm of a val.  
Let us define the val weighting matrix ''W'' to be the {{w|diagonal matrix}} with values 1, 1/log<sub>2</sub>3, 1/log<sub>2</sub>5 … 1/log<sub>2</sub>''p'' along the diagonal. [[Applying]] this matrix to a vector scales each entry by the corresponding entry of the diagonal matrix. Given a val '''a''' expressed as a row vector, the corresponding vector in weighted coordinates is {{nowrap|'''v''' {{=}} '''a'''''W''}}, with transpose {{nowrap|'''v'''{{t}} {{=}} ''W'''''a'''{{t}}}} where {{t}} denotes the transpose (writing the vector as a column vector instead of a row vector, as in the mathematical guide). Then the dot product of weighted vals is {{nowrap|'''vv'''{{t}} {{=}} '''a'''''W''&#x200A;<sup>2</sup>'''a'''{{t}}}} (the dot product of a vector with itself, or the sum of the squares of its entries), which makes the Euclidean metric on vals<sup>[how?]</sup>, a measure of complexity, to be {{nowrap|‖'''v'''‖<sub>2</sub> {{=}} √('''vv'''{{t}})}} {{nowrap|{{=}} √({{subsup|''a''|2|2}} + {{subsup|''a''|3|2}}/(log<sub>2</sub>3)<sup>2</sup> + … + {{subsup|''a''|''p''|2}}/(log<sub>2</sub>''p'')<sup>2</sup>)}}; dividing this by √(''n''), where {{nowrap|''n'' {{=}} π(''p'')}} is the number of primes to ''p'', gives the TE norm of a val.  


Similarly, if '''b''' is a monzo, then in weighted coordinates the monzo becomes {{nowrap|'''m''' {{=}} ''W''{{inv}}'''b'''}}, and the dot product is {{nowrap|'''m'''{{t}}'''m''' {{=}} '''b'''{{t}}''W''<sup>-2</sup>'''b'''}}, leading to {{nowrap|√('''m'''{{t}}'''m''') {{=}} √({{subsup|''b''|2|2}} + (log<sub>2</sub>3)<sup>2</sup>{{subsup|''b''|3|2}} + … + (log<sub>2</sub>''p'')<sup>2</sup>{{subsup|''b''|''p''|2}})}}; multiplying this by √(''n'') gives the dual RMS norm on monzos which serves as a measure of complexity.  
Similarly, if '''b''' is a monzo, then in weighted coordinates the monzo becomes {{nowrap|'''m''' {{=}} ''W''{{inv}}'''b'''}}, and the dot product is {{nowrap|'''m'''{{t}}'''m''' {{=}} '''b'''{{t}}''W''<sup>-2</sup>'''b'''}}, leading to {{nowrap|√('''m'''{{t}}'''m''') {{=}} √({{subsup|''b''|2|2}} + (log<sub>2</sub>3)<sup>2</sup>{{subsup|''b''|3|2}} + … + (log<sub>2</sub>''p'')<sup>2</sup>{{subsup|''b''|''p''|2}})}}; multiplying this by √(''n'') gives the dual RMS norm on monzos which serves as a measure of complexity.