typocomath/src/numbers/arithmetic.ts

import type {configDependency} from '../core/Config.js'
import type {Dependencies, Signature, RTT, DSignature} from '../interfaces/type.js'
import {$reflect, $Dreflect} from '../interfaces/type.js'

export const add:        Signature<'add',        number> & RTT = (a, b) => a + b
export const unaryMinus: Signature<'unaryMinus', number> = a => -a
export const conj:       DSignature<'conj',       number> = a => a
export const subtract =  (): Signature<'subtract',   number> => (a, b) => a - b
export const multiply:   Signature<'multiply',   number> = (a, b) => a * b
export const absquare:   Signature<'absquare',   number> = a => a * a
export const reciprocal: Signature<'reciprocal', number> = a => 1 / a
export const divide:     Signature<'divide',     number> = (a, b) => a / b

const basicSqrt = (a: number) => isNaN(a) ? NaN : Math.sqrt(a)
export const conservativeSqrt: Signature<'conservativeSqrt', number> = basicSqrt

export const sqrt =
  (dep: configDependency
   & Dependencies<'complex', number>): Signature<'sqrt', number> => {
    if (dep.config.predictable || !dep.complex) {
      return basicSqrt
    }
    return a => {
      if (isNaN(a)) return NaN
      if (a >= 0) return Math.sqrt(a)
      return dep.complex(0, Math.sqrt(unaryMinus(a)))
    }
   }
$reflect!([add, sqrt, subtract])
$Dreflect!([conj])