Cumulative standard deviation: Difference between revisions
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(→{{header|J}}: Simplify and add alternative) |
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<lang j> mean=: +/ % # |
<lang j> mean=: +/ % # |
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dev=: - mean |
dev=: - mean |
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stddevP=: [: %:@mean *:@dev |
stddevP=: [: %:@mean *:@dev NB. A) 3 equivalent defs for stddevP |
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stddevP=: [: mean&.:*: dev NB. B) uses Under (&.:) to apply inverse of *: after mean |
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stddevP=: %:@(mean@:*: - *:@mean) NB. C) sqrt of ((mean of squares) - (square of mean)) |
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stddevP\ 2 4 4 4 5 5 7 9 |
stddevP\ 2 4 4 4 5 5 7 9 |
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