通过调试语句放置修复了不一致的输出

EDIT：这是一个未初始化的变量…：（

说明：我使用的PointLLA构造函数只通过Latitude和Longitude，但我从未明确将内部Altitude成员变量设置为0。新手失误。。。

原始问题：我的代码中出现了一个错误，这让我很难过。我在计算一个点和一个矩形的角之间的距离。在这种情况下，点位于矩形的中心，所以我应该得到四个相等的距离。我得到三个相等的距离，还有一个几乎相等的不一致的距离值（每次运行都不同）。

如果我有几个关键的调试语句（几乎只是一个std:：cout调用）明确地打印出每个矩形角的位置，我就会得到距离的预期值，不一致性就会消失。这是相关代码：

// calculate the minimum and maximum distance to
// camEye within the available lat/lon bounds
Vec3 viewBoundsNE;   convLLAToECEF(PointLLA(maxLat,maxLon),viewBoundsNE);
Vec3 viewBoundsNW;   convLLAToECEF(PointLLA(maxLat,minLon),viewBoundsNW);
Vec3 viewBoundsSW;   convLLAToECEF(PointLLA(minLat,minLon),viewBoundsSW);
Vec3 viewBoundsSE;   convLLAToECEF(PointLLA(minLat,maxLon),viewBoundsSE);
// begin comment this block out, and buggy output
OSRDEBUG << "INFO: NE (" << viewBoundsNE.x
         << "  " << viewBoundsNE.y
         << "  " << viewBoundsNE.z << ")";
OSRDEBUG << "INFO: NW (" << viewBoundsNW.x
         << "  " << viewBoundsNW.y
         << "  " << viewBoundsNW.z << ")";
OSRDEBUG << "INFO: SE (" << viewBoundsSW.x
         << "  " << viewBoundsSW.y
         << "  " << viewBoundsSW.z << ")";
OSRDEBUG << "INFO: SW (" << viewBoundsSE.x
         << "  " << viewBoundsSE.y
         << "  " << viewBoundsSE.z << ")";
// --------------- end
// to get the maximum distance, find the maxima
// of the distances to each corner of the bounding box
double distToNE = camEye.DistanceTo(viewBoundsNE);
double distToNW = camEye.DistanceTo(viewBoundsNW); // <-- inconsistent
double distToSE = camEye.DistanceTo(viewBoundsSE);
double distToSW = camEye.DistanceTo(viewBoundsSW);
std::cout << "INFO: distToNE: " << distToNE << std::endl;
std::cout << "INFO: distToNW: " << distToNW << std::endl; // <-- inconsistent
std::cout << "INFO: distToSE: " << distToSE << std::endl;
std::cout << "INFO: distToSW: " << distToSW << std::endl;
double maxDistToViewBounds = distToNE;
if(distToNW > maxDistToViewBounds)
{   maxDistToViewBounds = distToNW;   }
if(distToSE > maxDistToViewBounds)
{   maxDistToViewBounds = distToSE;   }
if(distToSW > maxDistToViewBounds)
{   maxDistToViewBounds = distToSW;   }
OSRDEBUG << "INFO: maxDistToViewBounds: " << maxDistToViewBounds;

因此，如果我运行上面显示的代码，我将得到如下输出：

INFO: NE (6378137  104.12492  78.289415)
INFO: NW (6378137  -104.12492  78.289415)
INFO: SE (6378137  -104.12492  -78.289415)
INFO: SW (6378137  104.12492  -78.289415)
INFO: distToNE: 462.71851
INFO: distToNW: 462.71851
INFO: distToSE: 462.71851
INFO: distToSW: 462.71851
INFO: maxDistToViewBounds: 462.71851

正如预期的那样。请注意，所有distTo*值都是相同的。我可以一遍又一遍地运行这个程序，我会得到完全相同的输出。但现在，如果我注释掉我在上面代码中注意到的块，我会得到这样的东西：

INFO: distToNE: 462.71851
INFO: distToNW: 463.85601
INFO: distToSE: 462.71851
INFO: distToSW: 462.71851
INFO: maxDistToViewBounds: 463.85601

每次跑步的distToNW略有不同。为什么distToNW而不是其他值？我不知道。再跑几次：

463.06218
462.79352
462.76194
462.74772
463.09787
464.04648

所以。。。这是怎么回事？我试着清理/重建我的项目，看看是否有什么奇怪的事情发生，但无济于事。我将GCC 4.6.3与x86目标一起使用。

编辑：添加相关功能的定义。

void MapRenderer::convLLAToECEF(const PointLLA &pointLLA, Vec3 &pointECEF)
{
    // conversion formula from...
    // hxxp://www.microem.ru/pages/u_blox/tech/dataconvert/GPS.G1-X-00006.pdf
    // remember to convert deg->rad
    double sinLat = sin(pointLLA.lat * K_PI/180.0f);
    double sinLon = sin(pointLLA.lon * K_PI/180.0f);
    double cosLat = cos(pointLLA.lat * K_PI/180.0f);
    double cosLon = cos(pointLLA.lon * K_PI/180.0f);
    // v = radius of curvature (meters)
    double v = ELL_SEMI_MAJOR / (sqrt(1-(ELL_ECC_EXP2*sinLat*sinLat)));
    pointECEF.x = (v + pointLLA.alt) * cosLat * cosLon;
    pointECEF.y = (v + pointLLA.alt) * cosLat * sinLon;
    pointECEF.z = ((1-ELL_ECC_EXP2)*v + pointLLA.alt)*sinLat;
}
    // and from the Vec3 class defn
    inline double DistanceTo(Vec3 const &otherVec) const
    {
        return sqrt((x-otherVec.x)*(x-otherVec.x) +
                    (y-otherVec.y)*(y-otherVec.y) +
                    (z-otherVec.z)*(z-otherVec.z));
    }