Java中Vincenty公式的不寻常格式

Question

我正在接管一个项目，并且注意到，当使用vincenty公式时，它是以一种不寻常的方式编写的。它是这样写的：

    String direct(double distance, double initialBearing, double positionlat, double positionlong)  {
        // if (this.height != 0) throw new RangeError('point must be on the surface of
        // the ellipsoid');

        double φ1 = this.toRad(positionlat)/* .toRadians() */, λ1 = this.toRad(positionlong)/* .toRadians() */;
        double α1 = this.toRad(initialBearing);
        double s = distance;

        // allow alternative ellipsoid to be specified
        // double ellipsoid = /*this.datum ? this.datum.ellipsoid :*/
        // LatLonEllipsoidal.ellipsoids.WGS84;
        // const {a, b, f} = ellipsoid;
        double a = 6378137;
        double b = 6356752.314245;
        double f = 1 / 298.257223563;
        // double a = ellipsoid;
        // double b = ellipsoid;
        // double f = ellipsoid;

        double sinα1 = Math.sin(α1);
        double cosα1 = Math.cos(α1);

        double tanU1 = (1 - f) * Math.tan(φ1), cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1;
        double σ1 = Math.atan2(tanU1, cosα1); // σ1 = angular distance on the sphere from the equator to P1
        double sinα = cosU1 * sinα1; // α = azimuth of the geodesic at the equator
        double cosSqα = 1 - sinα * sinα;
        double uSq = cosSqα * (a * a - b * b) / (b * b);
        double A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
        double B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));

        double σ = s / (b * A);
        Double sinσ = null, cosσ = null, Δσ = null; // σ = angular distance P� P₂ on the sphere
        Double cos2σₘ = null; // σₘ = angular distance on the sphere from the equator to the midpoint of the
                                // line

        Double σʹ = null, iterations = 0d;
        do {
            cos2σₘ = Math.cos(2 * σ1 + σ);
            sinσ = Math.sin(σ);
            cosσ = Math.cos(σ);
            Δσ = B * sinσ * (cos2σₘ + B / 4 * (cosσ * (-1 + 2 * cos2σₘ * cos2σₘ)
                    - B / 6 * cos2σₘ * (-3 + 4 * sinσ * sinσ) * (-3 + 4 * cos2σₘ * cos2σₘ)));
            σʹ = σ;
            σ = s / (b * A) + Δσ;
        } while (Math.abs(σ - σʹ) > 1e-12 && ++iterations < 100);
        if (iterations >= 100) {
            //throw new Exception("Vincenty formula failed to converge"); // not possible?
            System.err.println("Warning: Vincenty formula failed to converge!");
        }
        

        double x = sinU1 * sinσ - cosU1 * cosσ * cosα1;
        double φ2 = Math.atan2(sinU1 * cosσ + cosU1 * sinσ * cosα1, (1 - f) * Math.sqrt(sinα * sinα + x * x));
        double λ = Math.atan2(sinσ * sinα1, cosU1 * cosσ - sinU1 * sinσ * cosα1);
        double C = f / 16 * cosSqα * (4 + f * (4 - 3 * cosSqα));
        double L = λ - (1 - C) * f * sinα * (σ + C * sinσ * (cos2σₘ + C * cosσ * (-1 + 2 * cos2σₘ * cos2σₘ)));
        double λ2 = λ1 + L;

        double α2 = Math.atan2(sinα, -x);

        // const destinationPoint = new
        // LatLonEllipsoidal_Vincenty(this.toDeg(φ2)/*.toDegrees()*/,
        // this.toDeg(λ2)/*.toDegrees()*/, 0, undefined);

        return this.toDeg(φ2) + ";" + this.toDeg(λ2);/*
                                                         * { lat: this.toDeg(φ2), lng: this.toDeg(λ2)
                                                         */
        /*
         * destinationPoint.g point: destinationPoint, finalBearing:
         * Dms.wrap360(this.toDeg(α2)/*.toDegrees()
         *//*
             * ), iterations: iterations,
             */
        // };
    }

现在IDE (eclipse)正在响应，它无法处理变量名，例如φ1。是否有一个优雅的解决方案来解决这个问题，还是我必须重写它？

Answer 1

很可能，源代码是用UTF-8编码编写的，您的Eclipse被配置为将源代码解释为ANSI、ISO-8859-1、cp1252或类似的代码。

然后，您看到的φ实际上是希腊字符phi (φ)的两字节UTF-8表示形式，根据ANSI解释。

配置Eclipse以期待UTF-8编码(Preferences / General / Workspace /文本文件编码)，然后它应该能够编译。

这个例子说明了为什么即使在今天在源代码中使用ASCII之外的字符也是个坏主意。