getDistanceSimple() returns NaN with specific parameters

[emcsween]

Not sure if it's the near equal longitudes, but this call returns NaN:

geolib.getDistanceSimple({latitude: 43.647862 , longitude: -79.39290290000002}, {latitude: 43.647862, longitude: -79.392903})

[jimmykane]

Same here. @manuelbieh the docs say its always a number I have more than 1.000 samples that validate that it returns NAN.

[manuelbieh]

Oh, that's weird. I'll investigate on this.

[jimmykane]

@manuelbieh thanks a lot for your time 👍 ! Nice library and project.

[manuelbieh]

This issue still exists and I have no clue why. I'll buy ice cream for whoever solves this.

[quocbaovu15101996]

I see it works normally. Tell me what wrong?

[projectpublius]

This issue still exists and I have no clue why. I'll buy ice cream for whoever solves this.

I just ran into this myself and I think I figured it out. It's an issue with floating point arithmetic when attempting to call getDistance() on two points that are the same or very close to the same point.

I have an app that records the user's path travelled over time, and sometimes the location is fixed for a short period leading to getDistance() being called on two copies of the same coordinate pair. The expected behavior is that getDistance() should return 0, which it does in most situations. But for certain coordinate pairs, e.g. { latitude: 38.95826, longitude: -77.44167 }, the getDistance() formula

const distance =
        Math.acos(
            Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) +
                Math.cos(toRad(toLat)) *
                    Math.cos(toRad(fromLat)) *
                    Math.cos(toRad(fromLon) - toRad(toLon))
        ) * earthRadius;

will evaluate to Math.acos(1.0000000000000002) instead of Math.acos(1) due to floating point arithmetic and will return NaN as a result.

This leads to getPathLength() also returning NaN if the array of points contains these coordinate pairs in sequence.

I think adding a Math.min(1,x) check to the distance formula should fix it:

const distance =
        Math.acos(Math.min(1,
            Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) +
                Math.cos(toRad(toLat)) *
                    Math.cos(toRad(fromLat)) *
                    Math.cos(toRad(fromLon) - toRad(toLon))
        )) * earthRadius;

[jimmykane]

Oh! That is a great catch !

On Fri, May 31, 2019 at 7:27 PM Jeff [email protected] wrote:

This issue still exists and I have no clue why. I'll buy ice cream for whoever solves this.

I just ran into this myself and I think I figured it out. It's an issue with floating point arithmetic when attempting to call getDistance() on two points that are the same or very close to the same point.

I have an app that records the user's path travelled over time, and sometimes the location is fixed for a short period leading to getDistance() being called on two copies of the same coordinate pair. The expected behavior is that getDistance() should return 0, which it does in most situations. But for certain coordinate pairs, e.g. { latitude: 38.95826, longitude: -77.44167 }, the getDistance() formula

const distance = Math.acos( Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) + Math.cos(toRad(toLat)) * Math.cos(toRad(fromLat)) * Math.cos(toRad(fromLon) - toRad(toLon)) ) * earthRadius;

will evaluate to Math.acos(1.0000000000000002) instead of Math.acos(1) due to floating point arithmetic and will return NaN as a result.

This leads to getPathLength() also returning NaN if the array of points contains these coordinate pairs in sequence.

A simple fix would be to add a Math.min(1,x) check to the distance formula:

const distance = Math.acos(Math.min(1, Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) + Math.cos(toRad(toLat)) * Math.cos(toRad(fromLat)) * Math.cos(toRad(fromLon) - toRad(toLon)) )) * earthRadius;

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[MajcenT]

Has anyone resolved the "getDistanceFromLine is returning NaN" issue? Are these two issues related?

[jimmykane]

I don't encounter this anymore

On Fri, 6 Mar 2020, 14:15 MajcenT, [email protected] wrote:

Has anyone resolved the "getDistanceFromLine is returning NaN" issue? Are these two issues related?

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[manuelbieh]

This should have been solved by adding a normalizeCosArg helper. Re-open if the error still occurs.

[casperkloppenburg]

I still encounter NaN values for these coordinates on [email protected]. Note that the supplied point is almost identical as the supplied lineStart.

Edit: Ah, I see you fixed this in 3.3.2. Geolib@latest on npm is still 3.3.1 though.

geolib.getDistanceFromLine({
  latitude: 53.0281161107639,
  longitude: 5.64420448614743,
}, {
  latitude: 53.028118,
  longitude: 5.644203,
}, {
  latitude: 53.029021,
  longitude: 5.646562,
})

geolib.getDistanceFromLine({
  latitude: 53.0515182362456,
  longitude: 5.67842625473533,
}, {
  latitude: 53.051521,
  longitude: 5.678421,
}, {
  latitude: 53.051652,
  longitude: 5.67852,
})

geolib.getDistanceFromLine({
  latitude: 53.0933224175307,
  longitude: 5.61011575344944,
}, {
  latitude: 53.093321,
  longitude: 5.610115,
}, {
  latitude: 53.093236,
  longitude: 5.610037,
})

geolib.getDistanceFromLine({
  latitude: 53.0867058030163,
  longitude: 5.59876618900706,
}, {
  latitude: 53.086705,
  longitude: 5.598759,
}, {
  latitude: 53.085538,
  longitude: 5.597901,
})

geolib.getDistanceFromLine({
  latitude: 53.0657207151762,
  longitude: 5.60056383087291,
}, {
  latitude: 53.065721,
  longitude: 5.600568,
}, {
  latitude: 53.062609,
  longitude: 5.600793,
})

[timvahlbrock]

Encountered this issue with 3.3.4 as well. See https://github.com/manuelbieh/geolib/pull/304 for faulty scenarios and fix. Fix found by @redcic75