//================================================================
/**
 * @packageDocumentation
 * @module std.internal
 */
//================================================================
import { MathUtil } from "./MathUtil";

export namespace Carlson {
    const INFINITY = 100 * 1000;
    const SECTION = INFINITY;

    export function rf(x: number, y: number, z: number): number {
        return (
            MathUtil.integral(
                function (t: number): number {
                    let ret: number = t + x;
                    ret *= t + y;
                    ret *= t + z;

                    return 1 / Math.sqrt(ret);
                },
                0,
                INFINITY,
                SECTION,
            ) / 2
        );
    }

    export function rj(x: number, y: number, z: number, p: number): number {
        return (
            MathUtil.integral(
                function (t: number): number {
                    let ret: number = t + x;
                    ret *= t + y;
                    ret *= t + z;
                    ret = (t + p) * Math.sqrt(ret);

                    return 1 / ret;
                },
                0,
                INFINITY,
                SECTION,
            ) * 1.5
        );
    }

    export function rc(x: number, y: number) {
        return rf(x, y, y);
    }

    export function rd(x: number, y: number, z: number) {
        return rj(x, y, z, z);
    }
}