10A. Sums & Means

`m0=: A=: # %~ +/`	Arithmetic mean
`m1=: G=: # %: */`	Geometric mean
`m2=: H=: A&.(%"_)`	Harmonic mean
`m3=: C=: [: {. (A,G)^:_`	Common mean; arithmetic-geometric mean (de Kerf [2])
`m4=: A&(^&3)`	Mean of cubes
`a5=: (^&) (A&)`	Generalized x-mean
`m6=: m4 -: 3 a5`	Tautology
`a7=: (^&) (A&.)`	L-x norm
`m8=: (^&3)@(3 a7) -: (3 a5)`	Tautology
`v9=: MA=: A\`	x-period moving average of `y`
`m10=: +/\ -: +/\.&.\|.`	Tautology: invariance under reverse
`m11=: +/\. -: +/\ &.\|.`	Tautology: invariance under reverse
m12=: +/\^:(i.`($&1))	Figurate numbers
`m13=: 1: #. ]`	Sum; `+/"1`
`m14=: +/&.(*:"_)@:+."0`	Magnitude `\|`
`m15=: - \|.!.0`	`.+/\^:_1`
`d16=: psum=: ([:+/ [ ^~ i.@])"0`	Sum of powers of integers; 2 sum 7
`m17=: 0&psum -: [`	Tautology: `+/(i.n)^0`
`m18=: 1&psum -: 2&!`	Tautology: `+/(i.n)^1`
`m19=: 2&psum -: 0 1r6 _1r2 1r3&p.`	Tautology: `+/(i.n)^2`
`m20=: [ (psum %. ^/~@]) i.@(2&+)`	Polynomial coeff. of `+/(i.n)^k`

JPhrases/SumsMeans