Comma basis: Difference between revisions
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{{Beginner|Dual list}} | {{Beginner|Dual list}} | ||
A '''comma basis''' is a [[basis]] for the | A '''comma basis''' is a [[basis]] for the {{w|Kernel (linear algebra)|nullspace}} (sometimes also called the "kernel") of a [[regular temperament|temperament]]. It consists of ''n'' {{w|linearly independent}} vectors, where ''n'' is the [[nullity]], each one representing a [[comma]] that is made to [[vanish]]. | ||
Linear independence means that no comma can be found as the sum of any multiples of the other commas. For example, consider the set of three commas 81/80, 126/125, and 225/224. As vectors those are {{vector|-4 4 -1 0}}, {{vector|1 2 -3 1}}, and {{vector|-5 2 2 -1}}. Notice that the third comma is actually the difference between the other two; {{nowrap|{{vector|-4 4 -1 0}} − {{vector|1 2 -3 1}} {{=}} {{vector|-5 2 2 -1}}}}, or as cents, {{nowrap|21.51{{c}} − 13.80{{c}} {{=}} 7.71{{c}}}}. So, if two of these three commas are ever made to vanish (mapped to 0{{c}}), then the third one necessarily is also made to vanish. Therefore, we only need to pick two of these commas to put in our comma basis; the third one would be implied. | Linear independence means that no comma can be found as the sum of any multiples of the other commas. For example, consider the set of three commas 81/80, 126/125, and 225/224. As vectors those are {{vector|-4 4 -1 0}}, {{vector|1 2 -3 1}}, and {{vector|-5 2 2 -1}}. Notice that the third comma is actually the difference between the other two; {{nowrap|{{vector|-4 4 -1 0}} − {{vector|1 2 -3 1}} {{=}} {{vector|-5 2 2 -1}}}}, or as cents, {{nowrap|21.51{{c}} − 13.80{{c}} {{=}} 7.71{{c}}}}. So, if two of these three commas are ever made to vanish (mapped to 0{{c}}), then the third one necessarily is also made to vanish. Therefore, we only need to pick two of these commas to put in our comma basis; the third one would be implied. | ||