LatLng distanceTo returns null for very close points

[bsterry]

LatLng.distanceTo() returns NaN for very close points on Nexus One API 22 emulator (does not repro in two other emulators I tried)

Sample code:
LatLng(40.00599, -105.29261).distanceTo(LatLng(40.005990000000025, -105.29260999999997)

Steps to reproduce

1. Call LatLng.distanceTo for two very near points (see above) on a Nexus One API 22 emulator (Android Studio, OSX)

Expected behavior

LatLng.distanceTo() returns 0.0 for any very close points

Actual behavior

LatLng.distnaceTo() returns NaN for some specific very close points in specific environments

It would seem that a test for isNaN(tt) is a safer way to implement this.

Configuration

OSX Android Studio emulator

Android versions:
Android 22

Device models:
Nexus One (emulated)

Mapbox SDK versions:
7.2

[bsterry]

Related to but not the same as issue 3556.

[bsterry]

I created a test to find more repros and found loads of very near location pairs that return NaN on my local machine (Android Studio, OSX, unit test)

import com.mapbox.mapboxsdk.geometry.LatLng
import org.junit.Test

class LatLngTest {
    @Test
    fun test() {
        val startLat = 40.0059514
        val startLng = -105.2927542

        val startLatLng = LatLng(startLat, startLng)

        val deltaLat = 40.005990000000025 - 40.00599
        val deltaLng = 105.29261 - 105.29260999999997

        println("offsets $deltaLat, $deltaLng")

        val deltaLats = listOf<Double>(deltaLat, 2.0 * deltaLat, 10.0 * deltaLat, 0.5 * deltaLat, 0.1 * deltaLat, 0.0, -deltaLat, 2.0 * -deltaLat, 10.0 * -deltaLat, 0.5 * -deltaLat, 0.1 * -deltaLat)
        val deltaLngs = listOf<Double>(deltaLng, 2.0 * deltaLng, 10.0 * deltaLng, 0.5 * deltaLng, 0.1 * deltaLng, 0.0, -deltaLng, 2.0 * -deltaLng, 10.0 * -deltaLng, 0.5 * -deltaLng, 0.1 * -deltaLng)

        for (i in 0..1000000) {
            val lat1 = Math.random() * 180.0 - 90.0
            val lng1 = Math.random() * 360.0 - 180.0

            val ll = LatLng(lat1, lng1)
            for (latDelta in deltaLats) {
                for (lngDelta in deltaLngs) {
                    val ll2 = LatLng(lat1 + latDelta, lng1 + lngDelta)
                    if (ll.distanceTo(ll2).isNaN()) {
                        println("NaN: $ll, $ll2, $latDelta, $lngDelta")
                    }

                }
            }
            if (i % 10000 == 0) {
                println(i)
            }
        }
    }
}

[bsterry]

Here is a snippet of output from the above test:

NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089849, altitude=0.0], 2.8421709430404007E-13, 2.8421709430404007E-13
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089876, altitude=0.0], 2.8421709430404007E-13, 1.4210854715202004E-14
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089878, altitude=0.0], 2.8421709430404007E-13, 2.842170943040401E-15
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089878, altitude=0.0], 2.8421709430404007E-13, 0.0
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.6713973008988, altitude=0.0], 2.8421709430404007E-13, -2.8421709430404007E-14
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089883, altitude=0.0], 2.8421709430404007E-13, -5.6843418860808015E-14
NaN: LatLng [latitude=-4.220846880803606, longitude=-68.67139730089878, altitude=0.0], LatLng [latitude=-4.220846880803322, longitude=-68.67139730089906, altitude=0.0], 2.8421709430404007E-13, -2.8421709430404007E-13