34 lines
1.2 KiB
JavaScript
34 lines
1.2 KiB
JavaScript
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import {promoteBinary, promoteUnary} from './helpers.js'
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import {Vector} from './Vector.js'
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import {ReturnType} from '#core/Type.js'
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import {match} from '#core/TypePatterns.js'
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import {ReturnsAs} from '#generic/helpers.js'
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export const normsq = match(Vector, (math, V) => {
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const compNormsq = math.normsq.resolve(V.Component)
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const sum = math.sum.resolve(Vector(ReturnType(compNormsq)))
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return ReturnsAs(sum, v => sum(v.map(compNormsq)))
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})
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// abs and norm differ only on Vector (and perhaps other collections) --
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// norm computes overall by the generic formula, whereas abs distributes
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// elementwise:
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export const abs = promoteUnary('abs')
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export const add = promoteBinary('add')
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export const sum = match(Vector, (math, V) => {
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const add = math.add.resolve([V.Component, V.Component])
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const haszero = math.haszero(V.Component)
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const zero = haszero ? math.zero(V.Component) : undefined
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return ReturnsAs(add, v => {
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if (v.length === 0) {
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if (haszero) return zero
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throw new TypeError(`Can't sum empty ${V}: no zero element`)
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}
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let ix = 0
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let retval = v[ix]
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while (++ix < v.length) retval = add(retval, v[ix])
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return retval
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})
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})
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