tsgammon-core/src/engines/Matrix.ts

A Backgammon library for Typescript, formerly developed as a part of tsgammon-ui

/**
 *
 * 行列計算の簡易な実装
 *
 * @module
 */

export type Matrix2d = {
    arr: number[][]

    rowsN(): number

    colsN(): number
}

export function matrix2d(value: number[][]): Matrix2d {
    return {
        arr: value,
        rowsN() {
            return this.arr.length
        },
        colsN() {
            return this.arr.length === 0 ? 0 : this.arr[0].length
        },
    }
}

export function product(m1: Matrix2d, m2: Matrix2d): Matrix2d {
    if (m1.colsN() !== m2.rowsN()) {
        throw Error()
    }
    const mp: number[][] = m1.arr.map((rowValues: number[], i) => {
        // rowValues = [a, b]
        const newRow: number[] = Array(m2.colsN()).fill(0)
        return newRow.map((v, j) => {
            return m1.arr[i]
                .map((v, ii) => {
                    return m2.arr[ii][j] * v
                })
                .reduce((a, b) => a + b)
        })
    })
    return matrix2d(mp)
}

export function add(m1: Matrix2d, m2: Matrix2d): Matrix2d {
    if (m1.rowsN() !== m2.rowsN() || m1.colsN() !== m2.colsN()) {
        throw Error()
    }

    return matrix2d(
        m1.arr.map((row, i) => {
            return row.map((value, j) => m2.arr[i][j] + value)
        })
    )
}