typocomath/src/Complex/arithmetic.ts

102 lines
3.8 KiB
TypeScript

import {Complex} from './type.js'
import type {
Dependencies, Signature, Returns, RealType, AliasOf
} from '../interfaces/type.js'
declare module "../interfaces/type" {
interface Signatures<T> {
addReal: AliasOf<'add', (a: T, b: RealType<T>) => T>
divideReal: AliasOf<'divide', (a: T, b: RealType<T>) => T>
}
}
export const add =
<T>(dep: Dependencies<'add' | 'complex', T>): Signature<'add', Complex<T>> =>
(w, z) => dep.complex(dep.add(w.re, z.re), dep.add(w.im, z.im))
export const addReal =
<T>(dep: Dependencies<'addReal' | 'complex', T>):
Signature<'addReal', Complex<T>> =>
(z, r) => dep.complex(dep.addReal(z.re, r), z.im)
export const unaryMinus =
<T>(dep: Dependencies<'unaryMinus' | 'complex', T>):
Signature<'unaryMinus', Complex<T>> =>
z => dep.complex(dep.unaryMinus(z.re), dep.unaryMinus(z.im))
export const conj =
<T>(dep: Dependencies<'unaryMinus' | 'conj' | 'complex', T>):
Signature<'conj', Complex<T>> =>
z => dep.complex(dep.conj(z.re), dep.unaryMinus(z.im))
export const subtract =
<T>(dep: Dependencies<'subtract' | 'complex', T>):
Signature<'subtract', Complex<T>> =>
(w, z) => dep.complex(dep.subtract(w.re, z.re), dep.subtract(w.im, z.im))
export const multiply =
<T>(dep: Dependencies<
'add' | 'subtract' | 'multiply' | 'conj' | 'complex', T>):
Signature<'multiply', Complex<T>> =>
(w, z) => {
const mult = dep.multiply
const realpart = dep.subtract(
mult( w.re, z.re), mult(dep.conj(w.im), z.im))
const imagpart = dep.add(
mult(dep.conj(w.re), z.im), mult( w.im, z.re))
return dep.complex(realpart, imagpart)
}
export const absquare =
<T>(dep: Dependencies<'absquare', T>
& Dependencies<'add', Returns<'absquare', T>>):
Signature<'absquare', Complex<T>> =>
z => dep.add(dep.absquare(z.re), dep.absquare(z.im))
export const divideReal =
<T>(dep: Dependencies<'divideReal' | 'complex', T>):
Signature<'divideReal', Complex<T>> =>
(z, r) => dep.complex(dep.divideReal(z.re, r), dep.divideReal(z.im, r))
export const reciprocal =
<T>(dep: Dependencies<'conj' | 'absquare' | 'divideReal', Complex<T>>):
Signature<'reciprocal', Complex<T>> =>
z => dep.divideReal(dep.conj(z), dep.absquare(z))
export const divide =
<T>(dep: Dependencies<'multiply' | 'reciprocal', Complex<T>>):
Signature<'divide', Complex<T>> =>
(w, z) => dep.multiply(w, dep.reciprocal(z))
// The dependencies are slightly tricky here, because there are three types
// involved: Complex<T>, T, and RealType<T>, all of which might be different,
// and we have to get it straight which operations we need on each type, and
// in fact, we need `addReal` on both T and Complex<T>, hence the dependency
// with a custom name, not generated via Dependencies<...>
export const sqrt =
<T>(dep: Dependencies<'equal' | 'conservativeSqrt' | 'unaryMinus', RealType<T>>
& Dependencies<'zero' | 'complex', T>
& Dependencies<'absquare' | 're' | 'divideReal', Complex<T>>
& {
addTR: Signature<'addReal', T>,
addRR: Signature<'add', RealType<T>>,
addCR: Signature<'addReal', Complex<T>>
}):
Signature<'sqrt', Complex<T>> =>
z => {
const myabs = dep.conservativeSqrt(dep.absquare(z))
const r = dep.re(z)
const negr = dep.unaryMinus(r)
if (dep.equal(myabs, negr)) {
// pure imaginary square root; z.im already zero
return dep.complex(
dep.zero(z.re), dep.addTR(z.im, dep.conservativeSqrt(negr)))
}
const num = dep.addCR(z, myabs)
const denomsq = dep.addRR(dep.addRR(myabs, myabs), dep.addRR(r, r))
const denom = dep.conservativeSqrt(denomsq)
return dep.divideReal(num, denom)
}
export const conservativeSqrt = sqrt